Tellurite resistance protein TehA/malic acid transport protein
Type:
Family
Description:
This entry includes TehA from Escherichia coli and Malic acid transport protein (Mae1) from Schizosaccharomyces pombe. TehA has been implicated in resistance to tellurite [
]. It has proflavin and ethidium efflux activity []. Mae1 functions in the uptake of malate and other dicarboxylates by a proton symport mechanism. These proteins exhibit 10 putative transmembrane a-helical spanners (TMSs).
Vacuolar protein sorting-associated protein 9, CUE domain
Type:
Domain
Description:
Vps9 is a cytosolic yeast protein required for localization of vacuolar proteins, such as the soluble vacuolar hydrolases CPY and PrA [
]. It may bind and act as an effector of a Rab GTPase and plays a role in vacuolar protein sorting (VPS) pathway. Vps9 contains a region called GBH domain that is related to mammalian Ras-binding proteins, Rin1 and JC265, and may negatively regulate Ras-mediated signaling in yeast Saccharomyces cerevisiae. This entry represents the N-terminal CUE domain that interacts specifically with monoubiquitin and regulates intramolecular monoubiquitylation [,
].
Myotubularin-related protein 3, protein tyrosine phosphatase domain
Type:
Domain
Description:
This entry represents the protein tyrosine phosphatase domain of Myotubularin-related protein 3 (Mtmf3). Proteins in this entry are specific to chordates. Mtmr3 is a phosphatase that acts on lipids with a phosphoinositol head-group such as phosphatidyl-inositol 3-phosphate and phosphatidyl-inositol 3,5-bisphosphate [
]. It may also de-phosphorylate proteins phosphorylated on Ser, Thr, and Tyr residues []. This enzyme has shown to play a regulatory role in the regulation of abscission, the final step of mitosis [], and innate immune responses to viral DNA through the modulation of STING trafficking [].
Myotubularin-related protein 4, protein tyrosine phosphatase domain
Type:
Domain
Description:
Myotubularin-related protein 4 (MTMR4) is a member of the myotubularin (MTM) family. It is the only family member that possesses a FYVE domain (a zinc finger domain) at its C terminus [
]. MTMR4 has dual-specificity phosphatase activity []; some studies have shown that it can dephosphorylate PI3P or PI(3,5)P2, suggesting that MTMR4 is also a lipid phosphatase []. MTMR4 has a unique distribution to endosomes [] and has been shown to function in early and recycling endosomes [,
]. MTMR4 attenuates TGF-beta signalling by dephosphorylating intracellular signalling mediator R-Smads []. Similarly, it acts as a negative modulator for the homeostasis of bone morphogenetic proteins (BMPs) signalling [].The myotubularin family constitutes a large group of conserved proteins, with 14 members in humans consisting of myotubularin (MTM1) and 13 myotubularin-related proteins (MTMR1-MTMR13). Orthologues have been found throughout the eukaryotic kingdom, but not in bacteria. MTM1 dephosphorylates phosphatidylinositol 3-monophosphate (PI3P) to phosphatidylinositol and phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] to phosphatidylinositol 5-monophosphate (PI5P) [,
]. The substrate phosphoinositides (PIs) are known to regulate traffic within the endosomal-lysosomal pathway []. MTMR1, MTMR2, MTMR3, MTMR4, and MTMR6 have also been shown to utilise PI(3)P as a substrate, suggesting that this activity is intrinsic to all active family members. On the other hand, six of the MTM family members encode for catalytically inactive phosphatases. Inactive myotubularin phosphatases contain substitutions in the Cys and Arg residues of the Cys-X5-Arg motif. MTM pseudophosphatases have been found to interact with MTM catalytic phosphatases []. The myotubularin family includes several members mutated in neuromuscular diseases or associated with metabolic syndrome, obesity, and cancer [].This entry represents the active Protein Tyrosine Phosphatase (PTP) domain of MTMR4.
Myotubularin-related protein 7, protein tyrosine phosphatase domain
Type:
Domain
Description:
Myotubularin-related protein 7 (MTMR7) is a member of the myotubularin (MTM) family. MTMR9 is a binding partner of MTMR7, and binding of MTMR9 increases the phosphatase activity of MTMR7 [
]. MTMR9 and MTMR7 may be involved in regulating T-helper (Th) cells differentiation [].The myotubularin family constitutes a large group of conserved proteins, with 14 members in humans consisting of myotubularin (MTM1) and 13 myotubularin-related proteins (MTMR1-MTMR13). Orthologues have been found throughout the eukaryotic kingdom, but not in bacteria. MTM1 dephosphorylates phosphatidylinositol 3-monophosphate (PI3P) to phosphatidylinositol and phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] to phosphatidylinositol 5-monophosphate (PI5P) [,
]. The substrate phosphoinositides (PIs) are known to regulate traffic within the endosomal-lysosomal pathway []. MTMR1, MTMR2, MTMR3, MTMR4, and MTMR6 have also been shown to utilise PI(3)P as a substrate, suggesting that this activity is intrinsic to all active family members. On the other hand, six of the MTM family members encode for catalytically inactive phosphatases. Inactive myotubularin phosphatases contain substitutions in the Cys and Arg residues of the Cys-X5-Arg motif. MTM pseudophosphatases have been found to interact with MTM catalytic phosphatases []. The myotubularin family includes several members mutated in neuromuscular diseases or associated with metabolic syndrome, obesity, and cancer [].MTMR7 contains a N-terminal PH-GRAM domain (
), a Rac-induced recruitment domain (RID) domain, an active Protein Tyrosine Phosphatase (PTP) domain (this entry), a SET-interaction domain, and a C-terminal coiled-coil region.
Myotubularin-related protein 1, protein tyrosine phosphatase domain
Type:
Domain
Description:
MTMR1 (myotubularin-related protein 1) is a lipid phosphatase that uses phosphatidylinositol 3-phosphate (PtdIns3P) and phosphatidylinositol 3,5-bisphosphate [PtdIns(3,5)P2] as substrates []. MTMR1 is abnormally expressed in myotonic dystrophy type1 (DM1) and in myotonic dystrophy type 2 (DM2), in correlation with muscle pathological features [
].The myotubularin family constitutes a large group of conserved proteins, with 14 members in humans consisting of myotubularin (MTM1) and 13 myotubularin-related proteins (MTMR1-MTMR13). Orthologues have been found throughout the eukaryotic kingdom, but not in bacteria. MTM1 dephosphorylates phosphatidylinositol 3-monophosphate (PI3P) to phosphatidylinositol and phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] to phosphatidylinositol 5-monophosphate (PI5P) [,
]. The substrate phosphoinositides (PIs) are known to regulate traffic within the endosomal-lysosomal pathway []. MTMR1, MTMR2, MTMR3, MTMR4, and MTMR6 have also been shown to utilise PI(3)P as a substrate, suggesting that this activity is intrinsic to all active family members. On the other hand, six of the MTM family members encode for catalytically inactive phosphatases. Inactive myotubularin phosphatases contain substitutions in the Cys and Arg residues of the Cys-X5-Arg motif. MTM pseudophosphatases have been found to interact with MTM catalytic phosphatases []. The myotubularin family includes several members mutated in neuromuscular diseases or associated with metabolic syndrome, obesity, and cancer [].This entry represents the active Protein Tyrosine Phosphatase (PTP) domain of MTMR1. This large domain is composed of seven β-strands and sixteen α-helices [
].
Yop protein translocation protein D, periplasmic domain
Type:
Domain
Description:
This entry represents the periplasmic domain of Yop proteins translocation protein D (YscD) from Proteobacteria. YscD forms part of the inner membrane component of the bacterial type III secretion injectosome apparatus [
,
].
Vacuolar protein sorting-associated protein 4, MIT domain
Type:
Domain
Description:
This entry represents the MIT domain found in vacuolar protein sorting-associated protein 4. The molecular function of the MIT domain is unclear [
].There are two mammalian VPS4 isoforms, VPS4A and VPS4B. They belong to the AAA ATPase family. VPS4A is a central regulator for early endosome trafficking [
,
]. VSP4 interacts with the ESCRT complex, which directs multiple cellular membrane remodelling events, ranging from the biogenesis of multivesicular bodies and exosomes to the final membrane abscission stage of cytokinesis []. The viral budding via host ESCRT complex can also be regulated by VPS4 [].
Testis-specific protein TEX28/transmembrane and coiled-coil domains protein
Type:
Family
Description:
This entry includes testis-specific TEX28 and transmembrane and coiled-coil domains protein 1/2/3 (TMCC1/2/3). TMCC1 is an ER protein. Overexpression of TMCC1 or its transmembrane domains has been shown to cause defects in ER morphology [
].The Drosophila TMCC2 is an an amyloid protein precursor-interacting and apolipoprotein E-binding protein. It is required for normal development of the brain [].
Protein of unknown function DUF463, YcjX-like protein
Type:
Family
Description:
This family represents a group of uncharacterised proteins including a bacterial stress protein YcjX. The crystal structure of YcjX from Shewanella oneidensis has now been solved, and shows it to be a Ras-like GTP-binding protein. However, YcjX utilizes a non-canonical switch 2' motif not found in any other G protein [
].
Myotubularin-related protein 10, protein tyrosine phosphatase domain
Type:
Domain
Description:
The family of myotubularin (MTM) phosphoinositide phosphatases includes catalytically inactive members, or pseudophosphatases, which contain inactivating substitutions in the phosphatase domain [
]. Myotubularin-related protein 10 (MTMR10) is a probable pseudophosphatase.This entry represents the inactive Protein Tyrosine Phosphatase (PTP) domain of MTMR10 [
].
Myelin protein zero-like protein 2, Ig-like domain
Type:
Domain
Description:
Myelin protein zero-like protein 2 (MPZL2), also known as epithelial V-like antigen (EVA), is a transmembrane protein that contains an extracellular immunoglobulin (Ig)-like V-type (variable) structural domain, and therefore has a putative role in cell adhesion. In mice Mpzl2 can compensate for the deficiency of Cadm1 (cell adhesion molecule-1) in the earlier spermatogenic cells [
]. It is is expressed in the thymus and in several epithelial structures early in embryogenesis, and therefore it may participate in the earliest phases of thymus organogenesis [].This entry represents the immunoglobulin (Ig)-like domain of MPZL2.
39S ribosomal protein L43/54S ribosomal protein L51
Type:
Family
Description:
This entry includes 39S ribosomal protein L43 (MRPL43) from animals and 54S ribosomal protein L51 (MRPL51) from fungi. They are components of the mitochondrial ribosome (mitoribosome), a dedicated translation machinery responsible for the synthesis of mitochondrial genome-encoded proteins [
].
Vacuolar protein sorting-associated protein 5, PX domain
Type:
Domain
Description:
The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Sorting nexins (SNXs) make up the largest group among PX domain containing proteins. They are involved in regulating membrane traffic and protein sorting in the endosomal system [
,
]. The PX domain of SNXs binds PIs and targets the protein to PI-enriched membranes. SNXs differ from each other in PI-binding specificity and affinity, and the presence of other protein-protein interaction domains, which help determine subcellular localization and specific function in the endocytic pathway [,
,
].Vsp5 is the yeast counterpart of human SNX1 and is part of the retromer complex, which functions in the endosome-to-Golgi retrieval of vacuolar protein sorting receptor Vps10, the Golgi-resident membrane protein A-ALP, and endopeptidase Kex2. The PX domain of Vps5 binds phosphatidylinositol-3-phosphate (PI3P). Similar to SNX1, Vps5 contains a Bin/Amphiphysin/Rvs (BAR) domain, which detects membrane curvature, C-terminal to the PX domain. Both domains have been shown to determine the specific membrane-targeting of SNX1 [
].
Chromo domain-containing protein cec-4/Chromobox protein homolog hpl-2
Type:
Family
Description:
Caenorhabditis elegans Cec-4 is a chromodomain protein that binds preferentially mono-, di-, or tri-methylated H3K9. It is necessary for endogenous heterochromatin anchoring, but not for transcriptional repression. Perinuclear sequestration of chromatin during development may help to restrict cell differentiation programs [
,
]. Also included in this entry is hlp-2, which also binds methylated H3K9, and unlike cec-4, it is required for transcriptional repression [,
].
Histidine-containing phosphotransfer protein 1-5/Phosphorelay intermediate protein YPD1
Type:
Family
Description:
This protein family includes the Histidine-containing phosphotransfer proteins 1-5 (AHP1-5) from Arabidopsis thaliana and the phosphorelay intermediate protein YPD1 from Saccharomyces cerevisiae and Candida albicans. Members of this entry are predominantly found in plants and fungi. The phospho-relay system is a variant of the two-component signal transduction system. Here a hybrid sensor histidine kinase (HK) auto-phosphorylates and then transfers the phosphoryl group to an internal receiver domain, rather than to a separate response regulator (RR) protein. The phosphoryl group is then shuttled to histidine phosphotransferase (HPT) and subsequently to a terminal RR, which can evoke the desired response [
,
]. AHP1-5 functions as two-component phosphorelay mediators between cytokinin sensor histidine kinases and response regulators. These proteins play an important role in propagating cytokinin signal transduction through the multistep phosphorelay, thus in the development of female gametophytes. They are localized in the cytoplasm and the nucleus [,
,
]. The phosphorelay intermediate protein YPD1 is part of the two-component regulatory system which controls gene expression in response to changes in the osmolarity of the extracellular environment. It catalyses the phosphoryl group transfer from the membrane-bound osmosensing histidine kinase SLN1 to two distinct response regulator proteins, SSK1 in the cytoplasm, and transcription factor SKN7 in the nucleus [
,
,
]. In C. albicans, this system is studied as a potential target for antifungal drugs [].
Vacuolar protein sorting-associated protein 33, domain 3b
Type:
Homologous_superfamily
Description:
Members of the Sec1 family include Sec1, Sly1, Slp1/Vps33, Vps45/Stt10 (yeast), Unc-18 (nematode), Munc-18b/muSec1, Munc-18c (mouse), Rop (Drosophila), Munc-18/n-Sec1/rbSec1A and rbSec1B (rat) [
].The nSec1 polypeptide chain can be divided into three domains. The first domain, consists of a five-stranded parallel β-sheet flanked by five α-helices. The second domain, like the first one, has an α-β-alpha fold, however the β-sheet of domain 2 features five parallel strands with an additional antiparallel strand on one edge. The third domain is a large insertion between the third and fourth parallel strands of domain 2, and can be subdivided in two [
].Vacuolar protein sorting-associated protein 33 (Vps33) is essential for vacuolar biogenesis, maturation and function. It is involved in the sorting of vacuolar proteins from the Golgi apparatus and their targeting to the vacuole [
]. In worm, fly, zebrafish and mammals two homologues of yeast Vps33p have been detected (termed VPS33A and VPS33B in humans). These homologues may reflect the evolution of organelle/tissue-specific functions in multicellular organisms. It is thought that VPS33B may be required for transport to conventional lysosomes, while VPS33A is mainly involved in biogenesis of melanosomes and related lysosomal compartments [,
].This superfamily entry represents the C-terminal region of domain 3 (called domain 3b) found in VPS33.
ABC transporter membrane protein permease protein ArtM/GltK/GlnP/TcyL/YhdX-like
Type:
Family
Description:
This entry represents the membrane component of a group of amino acid transport systems, including arginine ABC transporter permease protein ArtM [
], glutamine transport system permease protein GlnP, glutamate/aspartate import permease protein GltJ/GltK [,
], L-cystine transport system permease protein TcyL [], and uncharacterised proteins such as YhdX and YhdY.ABC transporters are minimally constituted of two conserved regions: a highly conserved ATP binding cassette (ABC) and a less conserved transmembrane domain (TMD). These regions can be found on the same protein (mostly in eukaryotes and bacterial exporters) or on two different ones (mostly bacterial importers) [
]. In importers, the TMD displays a distinctive signature, the EAA motif, a 20 amino acid conserved sequence located about 100 residues from the C terminus. The motif is hydrophilic and has been found to reside in a cytoplasmic loop located between the penultimate and the antepenultimate transmembrane segment in all proteins with a known topology []. It appears to play an important role in ensuring the correct assembly of the prokaryotic ABC transport complex [] and constituting an interaction site with the so-called helical domain of the ABC module [,
].
Vacuolar protein sorting-associated protein 13, extended chorein
Type:
Domain
Description:
This entry covers RBG modules that lie towards the N terminus, just downstream from
and has been described as extended chorein in [
]. These modules are involved in lipid binding and transport [,
,
] which specifically interacts with phosphatidic acid and phosphorylated forms of phosphatidyl inositol [].VPS13 proteins have been implicated in processes including vesicle fusion, autophagy, and actin regulation. They bind phospholipids and act as channels that mediate the transfer of lipids between membranes at organelle contact sites [
,
,
]. It has been proposed that members of this entry have the capacity to bind and likely transfer tens of glycerolipids at once. Yeast VPS13 acts at multiple cellular sites, namely the interface between mitochondria and the vacuole, on endosomes, on the nuclear-vacuole junction and the vacuole, depending on the carbon source and metabolic state. Most evidence showed that mammalian VPS13A, VPS13C and VPS13D localize at contacts between the ER and other organelles, i.e. VPS13A and VPS13D bridge the ER to mitochondria, VPS13C bridges the ER to late endosomes and lysosomes and VPS13B may localize to endosome-endosome contacts [,
,
]. Mutations in human VPS13 proteins (VPS13A-D) cause different diseases such as Chorea-acanthocytosis, Cohen syndrome, Parkinson's disease, and spastic ataxia, respectively which suggests they have different functions [,
]. Members of this entry belong to the repeating β-groove (RBG) superfamily. These proteins share a structure made of multiple repeating modules consisting of five β-sheets followed by a loop [].
Vacuolar protein sorting-associated protein 13, DH-like domain
Type:
Domain
Description:
This entry represents a domain reminiscent of a DH domain (DH-like domain) found adjacent the predicted C-terminal PH-like domain of VPS13 proteins [
,
,
,
]. DHL-PH domains has been identified as the mitochondria-binding region of VPS13A and the lipid droplet-binding region of both proteins. These two domains contain a region of high similarity to ATG2, which also binds lipid droplets [,
].VPS13 proteins have been implicated in processes including vesicle fusion, autophagy, and actin regulation. They bind phospholipids and act as channels that mediate the transfer of lipids between membranes at organelle contact sites [
,
,
]. It has been proposed that members of this entry have the capacity to bind and likely transfer tens of glycerolipids at once. Yeast VPS13 acts at multiple cellular sites, namely the interface between mitochondria and the vacuole, on endosomes, on the nuclear-vacuole junction and the vacuole, depending on the carbon source and metabolic state. Most evidence showed that mammalian VPS13A, VPS13C and VPS13D localize at contacts between the ER and other organelles, i.e. VPS13A and VPS13D bridge the ER to mitochondria, VPS13C bridges the ER to late endosomes and lysosomes and VPS13B may localize to endosome-endosome contacts [,
,
]. Mutations in human VPS13 proteins (VPS13A-D) cause different diseases such as Chorea-acanthocytosis, Cohen syndrome, Parkinson's disease, and spastic ataxia, respectively which suggests they have different functions [,
]. Members of this entry belong to the repeating β-groove (RBG) superfamily. These proteins share a structure made of multiple repeating modules consisting of five β-sheets followed by a loop [].
Protein tyrosine phosphatase receptor type C-associated protein
Type:
Family
Description:
This group represents protein tyrosine phosphatase receptor type C (PTPRC)-associated protein, also known as CD45-associated protein [
,
]. It is a positive regulator of PTPRC (CD45), which activates Src family kinases implicated in tumorigenesis [].
Retinoic acid-induced protein 2/sine oculis-binding protein homologue
Type:
Family
Description:
Retinoic acid (RA) has been shown to modulate the expression of a number of proteins implicated in the control of early embryonic development. One of these is retinoic acid-induced protein 2 (RAI2), which has been isolated in mouse [
] and humans [].Sine oculis-binding protein homologue (Jxc1, SOBP) is implicated in the development of the cochlea in the inner ear [
]. Mutations in this gene also cause intellectual disability (ID) [].
Insect odorant-binding protein A10/Ejaculatory bulb-specific protein 3
Type:
Family
Description:
This entry represents the insect odorant-binding protein A10, also known as OS-D or pherokine-1, and ejaculatory bulb-specific protein 3 (PebIII), also known as pherokine-2 [
]. Odorant binding proteins (OBPs) is a class of small (14-20 Kd) water-soluble proteins first discovered in the insect sensillar lymph but also in the mucus of vertebrates, is postulated to mediate the solubilisation of hydrophobic odorant molecules, and thereby to facilitate their transport to the receptor neurons. The product of a gene expressed in the olfactory system of Drosophila melanogaster (Fruit fly), OS-D, shares features common to vertebrate odorant-binding proteins, but has a primary structure unlike odorant-binding proteins []. OS-D derivatives have subsequently been found in chemosensory organs of phylogenetically distinct insects, including cockroaches, phasmids and moths, suggesting that OS-D-like proteins seem to be conserved in the insect phylum.
Myotubularin-related protein 8, protein tyrosine phosphatase domain
Type:
Domain
Description:
Myotubularin-related protein 8 (MTMR8) is a catalytically active member of the myotubularin (MTM) family, which possess 3-phosphatase activity dephosphorylating phosphatidylinositol-3-phoshate [PI(3)P] and phosphatidylinositol-3,5-bisphosphate [PI(3,5)P]. MTMR8 dimerises with the catalytically inactive MTMR9. Complex formation increases its catalytic activity and alters the substrate specificity; the MTMR8/R9 complex prefers PI(3)P as a substrate and reduces cellular PtdIns(3)P levels [
,
]. The MTMR8/R9 complex inhibits autophagy []. In zebrafish, MTMR8 has been shown to cooperate with PI3K to regulate actin filament modeling, and vascular and muscle development [,
].The myotubularin family constitutes a large group of conserved proteins, with 14 members in humans consisting of myotubularin (MTM1) and 13 myotubularin-related proteins (MTMR1-MTMR13). Orthologues have been found throughout the eukaryotic kingdom, but not in bacteria. MTM1 dephosphorylates phosphatidylinositol 3-monophosphate (PI3P) to phosphatidylinositol and phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] to phosphatidylinositol 5-monophosphate (PI5P) [,
]. The substrate phosphoinositides (PIs) are known to regulate traffic within the endosomal-lysosomal pathway []. MTMR1, MTMR2, MTMR3, MTMR4, and MTMR6 have also been shown to utilise PI(3)P as a substrate, suggesting that this activity is intrinsic to all active family members. On the other hand, six of the MTM family members encode for catalytically inactive phosphatases. Inactive myotubularin phosphatases contain substitutions in the Cys and Arg residues of the Cys-X5-Arg motif. MTM pseudophosphatases have been found to interact with MTM catalytic phosphatases []. The myotubularin family includes several members mutated in neuromuscular diseases or associated with metabolic syndrome, obesity, and cancer [].This entry represents the active Protein Tyrosine Phosphatase (PTP) domain of MTMR8. Its catalytic activity is inhibited by oxidation and is reversibly reactivated by reduction [
].
Nck-associated protein 1 is part of lamellipodial complex that controls Rac-dependent actin remodeling [
,
]. It associates preferentially with the first SH3 domain of Nck and is a component of the WAVE2 complex composed of ABI1, CYFIP1/SRA1, NCKAP1/NAP1 and WASF2/WAVE2. It is also a component of the WAVE1 complex composed of ABI2, CYFIP2, C3orf10/HSPC300, NCKAP1 and WASF1/WAVE1. CYFIP2 binds to activated RAC1 which causes the complex to dissociate, releasing activated WASF1. The complex can also be activated by NCK1. Expression of this protein was found to be markedly reduced in patients with Alzheimer's disease [].
Extensins are plant cell-wall proteins; they can account for up to 20% of
the dry weight of the cell wall. They are highly-glycosylated, possiblyreflecting their interactions with cell-wall carbohydrates. Amongst their
functions is cell wall strengthening in response to mechanical stress (e.g.,during attack by pests, plant-bending in the wind, etc.).
By contrast with extensin genes, pistil-specific extensin-like genes arenot induced under stress conditions. Gene expression is organ-specific
and temporally regulated during pistil development. After pollination, transcript levels of pistil-specific extensin-like genes change relative to
levels in unpollinated pistils []. The protein sequence is characterisedby multiple tandem ser-pro-pro-pro-pro pentapeptide repeats.
Segregation of nuclear and cytoplasmic processes facilitates regulation of many eukaryotic cellular functions such as gene expression and cell cycle progression. Trafficking through the nuclear pore requires a number of highly conserved soluble factors that escort macromolecular substrates into and out of the nucleus. The Mog1 protein has been shown to interact with RanGTP, which stimulates guanine nucleotide release, suggesting Mog1 regulates the nuclear transport functions of Ran [
]. The human homologue of Mog1 is thought to be alternatively spliced.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].This family consists of bacterial (and chloroplast) examples of the ribosomal small subunit protein S20. Bacterial ribosomal protein S20 forms part of the 30S ribosomal subunit, and interacts with 16S rRNA.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].A variety of eukaryotic and plant ribosomal L10e proteins can be grouped.
This family consists of vertebrate L10 (QM) [], plant L10, Caenorhabditis elegans L10, yeast L10 (QSR1) andMethanocaldococcus jannaschii (Methanococcus jannaschii) MJ0543.
RHIP1 provides a physical connection between the glucose signaling sensors RGS1 and HXK1, and is required for some glucose-regulated gene expression in plants [
].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].This entry represents the S27a ribosomal domain from both archaea and eukaryotes. In eukaryotes, the 40S ribosomal protein S27a is synthesized as a C-terminal extension of ubiquitin (
), and this fusion protein is known as UBS27 [
]. The S27a domain compromises the C-terminal half of the protein. The synthesis of ribosomal proteins as extensions of ubiquitin promotes their incorporation into nascent ribosomes by a transient metabolic stabilisation and is required for efficient ribosome biogenesis []. The ribosomal extension protein S27a contains a basic region that is proposed to form a zinc finger; its fusion gene is proposed as a mechanism to maintain a fixed ratio between ubiquitin necessary for degrading proteins and ribosomes a source of proteins [].
Centromere protein X (CENP-X) is a component of several different complexes, including the multisubunit FA complex, the heterotetrameric CENP-T-W-S-X complex and the APITD1/CENPS complex. The Fanconi anemia (FA) core complex is involved in DNA damage repair and genome maintenance. The FA complex is composed of CENPS, FANCA, FANCB, FANCC, FANCE, FANCF, FANCG, FANCL/PHF9, FANCM, FAAP24 and CENPX. Interacts with CENPS, FANCM and FAAP24 [
,
]. Inner kinetochore subunit mhf2 is the dsDNA-binding component of the FANCM-MHF complex, important for gene conversion at blocked replication forks [] and non-crossover recombination during mitosis and meiosis [].The CENP-T-W-S-X complex binds, supercoils DNA and plays an important role in kinetochore assembly [
].The APITD1/CENPS complex is composed of at least of CENP-S and CENP-X and is essential for the stable assembly of the outer kinetchore [
].
This family includes Transmembrane protein 106A/B/C, type II transmembrane proteins which have homology to the late embryogenesis abundant-2 (LEA-2) domain [
]. TMEM106A has been identified as a key factor to regulate macrophage activation and a tumor suppressor in gastric, renal cancer and nonsmall-cell lung carcinoma (NSCLC), being an interesting therapeutic target for the management of NSCLC [,
]. TMEM106B localises to late endosomes and lysosomes, and it is involved in dendrite morphogenesis and maintenance by regulating lysosomal trafficking via its interaction with MAP6 []. Its overexpression is associated with familial frontotemporal lobar degeneration []. It has also been identified as a protein required for productive SARS-CoV-2 infection [
]. Structural analysis of LEA-2 domains revealed that they have a long, conserved lipid-binding groove, implying that TMEM106B and its homologues, Vac7 and Tag1 from yeast, may all be lipid transfer proteins in the lumen of late endocytic organelles.
Kinetochores are the chromosomal sites for spindle interaction and play a vital role for chromosome segregation. Fission Saccharomyces cerevisiae kinetochore protein Mis12, is required for correct spindle morphogenesis, determining metaphase spindle length [
]. Thirty-five to sixty percent extension of metaphase spindle length takes place in Mis12 mutants []. It has been shown that Mis12 might genetically interact with Mal2p [].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].Ribosomal protein L36 is the smallest protein from the large subunit of the prokaryotic ribosome. It belongs to a family of ribosomal proteins which, on the basis of sequence similarities can be grouped into: bacterial L36; algal and plant chloroplast L36; Cyanelle L36. L36 is a small basic and cysteine-rich protein of 37 amino-acid residues.
Macroautophagy is a bulk degradation process induced by starvation in eukaryotic cells. In yeast, 15 Atg proteins coordinate the formation of autophagosomes. The pre-autophagosomal structure contains at least five Atg proteins: Atg1p, Atg2p, Atg5p, Aut7p/Atg8p and Atg16p, found in the vacuole [
,
]. The C-terminal glycine of Atg12p is conjugated to a lysine residue of Atg5p via an isopeptide bond. During autophagy, cytoplasmic components are enclosed in autophagosomes and delivered to lysosomes/vacuoles. Autophagy protein 16 (Atg16) has been shown to bind to Atg5 and is required for the function of the Atg12p-Atg5p conjugate []. Autophagy protein 5 (Atg5) is directly required for the import of aminopeptidase I via the cytoplasm-to-vacuole targeting pathway [].This entry represents the C-terminal domain of Atg12, which is covalently bound to Atg5 [
].
Ribosomal protein S1 [
] contains the S1 domain that has been found in a large number of RNA-associated proteins. S1 is a prominent component of the Escherichia coli ribosome and is most probably required for translation of most, if not all, natural mRNAs in E. coli in vivo []. It has been suggested that S1 is a RNA-binding protein helping polynucleotide phosphorylase (PNPase, known to be phylogenetically related to S1) to degrade mRNA, or helper molecule involved in other RNase activities [
]. Unique among ribosomal proteins, the primary structure of S1 contains four repeating homologous stretches in the central and terminal region of the molecule. S1 is organised into at least two distinct domains; a ribosome-binding domain at the N-terminal region and a nucleic acid-binding domain at the C-terminal region [
]. There may be a flexible region between the two domains permitting free movement of the domains relative to each other.Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].
This entry represents a family plant proteins, including At3g61320 from Arabidopsis thaliana (also known as ATVCCN1 or BESTROPHIN-LIKE PROTEIN), which is a chloride channel required for ion transport and homeostasis across the thylakoid membrane to adjust photosynthesis according to the light environment [
,
,
].
This entry consists of the mitochondrial 39S ribosomal protein L28, mitochondrial 54S ribosomal protein L24 and 50S ribosomal protein L28. They belong to the ribosomal protein L28 family. They are components of the mitochondrial or non-mitochondrial large ribosomal subunits.Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].The ribosomal L28 protein family include proteins from bacteria
and chloroplasts. The L24 protein from yeast, found in the large subunit of the mitochodrial ribosome, contains a region similar to the bacterial L28 protein.
Members of this group include the archaeal protein Alba and eukaryotic Ribonuclease P subunits Pop7/Rpp20 and Rpp25. The Alba domain is closely related to the RNA-binding versions of the IF3-C fold such as YhbY and IF3-C. The eukaryotic lineages of the Alba family are principally involved in RNA metabolism, suggesting that the ancestral function of the IF3-C fold was related to RNA interaction [
].Alba has been shown to bind DNA and affect DNA supercoiling in a temperature dependent manner [
]. It is regulated by acetylation (alba = acetylation lowers binding affinity) by the Sir2 protein. Alba is proposed to play a role in establishment or maintenance of chromatin architecture and thereby in transcription repression. For further information see [].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].Ribosomal protein L14 is one of the proteins from the large ribosomal subunit.
In eubacteria, L14 is known to bind directly to the 23S rRNA. It belongs to a family of ribosomal proteins, which have been grouped on the basis of sequence similarities. Based on amino-acid sequence homology, it is predicted that ribosomal protein L14 is a member of a recently identified family of structurally related RNA-binding proteins []. L14 is a protein of 119 to 137 amino-acid residues.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].A number of eukaryotic and archaeal ribosomal proteins can be grouped on the basis of sequence similarities. One of these families consists of proteins of 56 to 96 amino-acid residues that share a highly conserved region located in the N-terminal part.
The ribosomal proteins catalyse ribosome assembly and stabilise the rRNA, tuning the structure of the ribosome for optimal function. Evidence suggests that, in prokaryotes, the peptidyl transferase reaction is performed by the large subunit 23S rRNA, whereas proteins probably have a greater role in eukaryotic ribosomes. Most of the proteins lie close to, or on the surface of, the 30S subunit, arranged peripherally around the rRNA [
]. The small subunit ribosomal proteins can be categorised as primary binding proteins, which bind directly and independently to 16S rRNA; secondary binding proteins, which display no specificaffinity for 16S rRNA, but its assembly is contingent upon the presence of one or more primary binding proteins; and tertiary binding proteins, which require the presence of one or more secondary binding proteins and sometimes other tertiary binding proteins.
The small ribosomal subunit protein S17 is known to bind specifically to the 5' end of 16S ribosomal RNA in Escherichia coli (primary rRNA binding protein), and is thought to be involved in the recognition of termination codons. Experimental evidence [] has revealed that S17 has virtually no groups exposed on the ribosomal surface.This ribosomal protein family includes 30S ribosomal protein S17 and 40S ribosomal protein S11.
This entry consists of proteins from eukaryotes and prokarytotes. It includes Escherichia coli autoinducer-2 (AI-2) transport protein TqsA (YdgG), which controls the transport of the quorum-sensing signal AI-2 either by enhancing its secretion or inhibiting its uptake and consequently represses biofilm formation and motility and affects the global gene expression in biofilms [
]. TqsA exhibit a uniform topology with 8 putative transmembrane segments (TMSs), a structure shared by proteins in this family. The function of proteins in this family are mostly unknown, however, it has been suggested that they may transport a variety of compounds, possibly all related in structure []. This entry also includes transport proteins such as sodium-lithium/proton antiporter from Halobacillus [] and sporulation protein YtvI from Bacillus subtilis, a putative permease [].This entry also includes uncharacterised transmembrane protein 245 (TMEM245) from eukaryotes.
This entry represents a group of DNA binding proteins, known as SBP (SQUAMOSA-pROMOTER BINDING PROTEIN) family. They are putative transcription factors characterised by a highly conserved SBP-box of 76 amino acids involved in DNA binding and nuclear localisation [
]. They are involved in the control of early flower development []. This entry includes Arabidopsis SPL3 and SPL4 []. SPL3/SPL4 promote vegetative phase change and flowering, and are strongly repressed by miR156 [].
This family contains several plant dormancy-associated and auxin-repressed proteins [
]. The expression of the DRM/ARP family members may be regulated by stress and environmental factors [].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [,
].A number of eukaryotic and archaeal ribosomal proteins have been grouped on the basis of sequence similarities. Ribosomal protein S6 is the major substrate of protein kinases in eukaryotic ribosomes [
] and may play an important role in controlling cell growth and proliferationthrough the selective translation of particular classes of mRNA.
The La protein is a 47kDa polypeptide that often acts as an autoantigen in systemic lupus erythematosus and Sjogren's syndrome patients [
]. It occurs in both the nucleus and the cytoplasm, where it takes on different roles []. In the nucleus, La facilitates the production of tRNAs, acting as a RNA polymerase III (RNAP III) transcription factor by binding to the U-rich 3'UTR of nascent transcripts, assisting in their folding and maturation []. In the cytoplasm, La facilitates the translation of specific mRNAs, acting as a translation factor. As a RNA binding protein (RBP), La associates with subsets of mRNAs that contain a 5'-terminal oligopyrimidine (5'TOP) motif known to control protein synthesis. The binding of La to specific classes of RNA molecules regulates their downstream processing, protects them from endonuclease digestion, and organises their export from the nucleus [,
,
,
].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].Ribosomal protein L34 is one of the proteins from the large subunit of the prokaryotic ribosome. It is a small basic protein of 44 to 51 amino-acid residues [
]. L34 belongs to a family of ribosomal proteins which, on the basis of sequence similarities, groups: Eubacterial L34, Red algal chloroplast L34 and Cyanelle L34.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].S27 is involved in rRNa processing, direct binding to mRNA and degradation of damaged mRNAs. S27 is a C4 zinc finger protein of the CX2CX14-16CX2C class. Zinc finger motifs in ribosomal proteins mediate protein-RNA interactions, however it has been suggested the zinc finger in S27 possibly has no functional importance for modern S27 proteins, and is rather a fossil from ancient evolution. This view is supported by the sequence alignment, showing that the zinc finger motif is not strictly conserved [
]. A number of eukaryotic and archaeal ribosomal proteins can be grouped on the basis of sequence similarities. One of these families include mammalian, yeast, Chlamydomonas reinhardtii and Entamoeba histolytica S27, and Methanocaldococcus jannaschii (Methanococcus jannaschii) MJ0250 [].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].L6 is a protein from the large (50S) subunit. In Escherichia coli, it is located in the aminoacyl-tRNA binding
site of the peptidyltransferase centre, and is known to bind directly to 23S rRNA. It belongs to a family of ribosomal proteins, including L6 from bacteria, cyanelles (structures that perform similar functions to chloroplasts, but have structural and biochemical characteristics of Cyanobacteria) and mitochondria; and L9 from mammals, Drosophila, plants and yeast. L6 contains two domains with almost identical folds, suggesting that is was derived by the duplication of an
ancient RNA-binding protein gene. Analysis reveals several sites on the protein surface where interactions with other ribosome components may occur, the N terminus being involved in protein-protein interactions and the C terminus containing possible RNA-binding sites [].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].Ribosomal protein L31 is one of the proteins from the large ribosomal subunit. L31 is a protein of 66 to 97 amino-acid residues which has only been found so far in bacteria and in some plant and algal chloroplasts.
Histidine is formed by several complex and distinct biochemical reactions catalysed by eight enzymes. Proteins involved in steps 4 and 6 of the histidine biosynthesis pathway are contained in one family. These enzymes are called His6 and His7 in eukaryotes and HisA and HisF in prokaryotes. HisA is a phosphoribosylformimino-5-aminoimidazole carboxamide ribotide isomerase (
), involved in the fourth step of histidine biosynthesis. The bacterial HisF protein is a cyclase which catalyses the cyclization reaction that produces D-erythro-imidazole glycerol phosphate during the sixth step of histidine biosynthesis. The yeast His7 protein is a bifunctional protein which catalyses an amido-transferase reaction that generates imidazole-glycerol phosphate and 5-aminoimidazol-4-carboxamide. The latter is the ribonucleotide used for purine biosynthesis. The enzyme also catalyses the cyclization reaction that produces D-erythro-imidazole glycerol phosphate, and is involved in the fifth and sixth steps in histidine biosynthesis.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].Ribosomal protein S11 [
] plays an essential role in selecting the correct tRNA in protein biosynthesis. It is located on the large lobe of the small ribosomal subunit. S14 is the eukaryotic homologue of S11; they constitute the uS11 family that includes bacterial, archaeal and eukaryotic proteins [].
Ferritin is one of the major non-haem iron storage proteins in animals, plants, and microorganisms [
]. It consists of a mineral core of hydrated ferric oxide, and a multi-subunit protein shell that encloses the former and assures its solubility in an aqueous environment.In animals the protein is mainly cytoplasmic and there are generally two or more genes that encode closely related subunits - in mammals there are two subunits which are known as H(eavy) and L(ight). In plants ferritin is found in the chloroplast [
].This entry represents the main structural domain of ferritin. The domain is also found in other ferritin-like proteins such as members of the DNA protection during starvation (DPS) family [
] and bacterioferritins [].
This entry represents the eukaryotic transmembrane proteins 230 and 134 (TMEM230 and 134). TMEM134 function is unknown, but it has been shown to interact with E virus ORF2 [
]. TMEM 230 is involved in trafficking and recycling of synaptic vesicles [].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].A number of eukaryotic ribosomal proteins can be grouped on the basis of sequence similarities. The L36E ribosomal family consists of mammalian, Caenorhabditis elegans and Drosophila L36, Candida albicans L39, and yeast YL39 ribosomal proteins [
].
Ndc1 is a nucleoporin protein that is a component of the Nuclear Pore Complex, and, in fungi, also of the Spindle Pole Body. It consists of six transmembrane segments, three luminal loops, both concentrated at the N terminus and cytoplasmic domains largely at the C terminus, all of which are well conserved.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].This family of large subunit ribosomal proteins is called the L7/L12 family. L7/L12 is present in each 50S subunit in four copies organised as two dimers. The L8 protein complex consisting of two dimers of L7/L12 and L10 in Escherichia coli ribosomes is assembled on the conserved region of 23 S rRNA termed the GTPase-associated domain [
]. L7 and L12 are identical except that L7 is acetylated at the N terminus. It is a component of the L7/L12 stalk, which is located at the surface of the ribosome. The stalk base consists of a portion of the 23S rRNA and ribosomal proteins L11 and L10. An extended C-terminal helix of L10 provides the binding site for L7/L12. L7/L12 consists of two domains joined by a flexible hinge, with the helical N-terminal domain (NTD) forming pairs of homodimers that bind to the extended helix of L10. It is the only multimeric ribosomal component, with either four or six copies per ribosome that occur as two or three dimers bound to the L10 helix. L7/L12 is the only ribosomal protein that does not interact directly with rRNA, but instead has indirect interactions through L10. The globular C-terminal domains of L7/L12 are highly mobile. They are exposed to the cytoplasm and contain binding sites for other molecules. Initiation factors, elongation factors, and release factors are known to interact with the L7/L12 stalk during their GTP-dependent cycles. The binding site for the factors EF-Tu and EF-G comprises L7/L12, L10, L11, the L11-binding region of 23S rRNA, and the sarcin-ricin loop of 23S rRNA. Removal of L7/L12 has minimal effect on factor binding and it has been proposed that L7/L12 induces the catalytically active conformation of EF-Tu and EF-G, thereby stimulating the GTPase activity of both factors [
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
].In eukaryotes, the proteins that perform the equivalent function to L7/L12 are called P1 and P2, which do not share sequence similarity with L7/L12. However, a bacterial L7/L12 homologue is found in some eukaryotes, in mitochondria and chloroplasts [
]. In archaea, the protein equivalent to L7/L12 is called aL12 or L12p, but it is closer in sequence to P1 and P2 than to L7/L12 [].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].A number of eukaryotic and archaebacterial ribosomal proteins belong to the L34e
family. These include, vertebrate L34, mosquito L31 [], plant L34 [],yeast putative ribosomal protein YIL052c and archaebacterial L34e.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].Ribosomal protein S9 is one of the proteins from the small ribosomal subunit. It belongs to the S9P family of ribosomal proteins which, on the basis of sequence similarities [
], groups bacterial; algal chloroplast; cyanelle and archaeal S9 proteins; and mammalian, plant, and yeast mitochondrial ribosomal S9 proteins. These proteins adopt a β-α-β fold similar to that found in numerous RNA/DNA-binding proteins, as well as in kinases from the GHMP kinase family [].
This entry describes a universal, mostly one-gene-per-genome GTP-binding protein that associates with ribosomal subunits and appears to play a role in ribosomal RNA maturation. Mutations in this gene are pleiotropic, but it appears that effects on cellular functions such as chromosome partition may be secondary to the effect on ribosome structure.This is an essential GTPase which binds GTP, GDP and ppGpp with moderate affinity (with a twofold preference for GDP over GTP); shows high guanine nucleotide exchange rate constants for both nucleotides, and has a relatively low GTP hydrolysis rate. Deletion of the N terminus makes a protein that is non-functional in vivo but which retains nucleotide binding and GTPase activity. Required for cell cycle progression from G1 to S phase and for DNA replication [
].
This entry includes the eukaryotic 60S ribosomal protein L18ae [
] the archaea 50S ribosomal protein LX and higher eukaryote 60S ribosomal protein L18A. Rat ribosomal protein L18 is homologous to Xenopus laevis L14 [].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].The ribosomal L35A eukaryotic and archaebacterial ribosomal proteins can be grouped on the basis of sequence similarities. One of these families consists of:
Vertebrate L35A.Caenorhabditis elegans L35A (F10E7.7).Saccharomyces cerevisiae L37A/L37B (Rp47).Plant L35A.Pyrococcus woesei L35A homologue [
].These proteins have 87 to 110 amino-acid residues.
This group of proteins have a conserved C-terminal region which is found in LMBR1 and in the lipocalin-1 receptor. LMBR1 was thought to play a role in preaxial polydactyly, but recent evidence now suggests this not to be the case [
]. Vertebrate members of this family may play a role in limb development []. Lysosomal cobalamin transport escort protein LMBD1 is a lysosomal membrane chaperone required to export cobalamin from lysosome to the cytosol, allowing its conversion to cofactors [,
]. This protein showed homology to the lipocalin membrane receptor (LIMR) [].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].The small subunits of bacterial and eukaryotic ribosomes have the same overall shapes (with structural elements described as head, body, platform, beak and shoulder). Ribosomal protein S6 is one of the proteins from the small ribosomal subunit. [
]. In Escherichia coli, S6 is known to bind together with S18 to 16S ribosomal RNA. It belongs to a family of ribosomal proteins which, on the basis of sequence similarities, groups bacterial, red algal chloroplast and cyanelle S6 ribosomal proteins.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [,
].A number of eukaryotic and archaeabacterial ribosomal proteins can be grouped on the basis of sequence
similarities. One of these families [] consists of mammalian ribosomal protein L24; yeastribosomal protein L30A/B (Rp29) (YL21); Kluyveromyces lactis ribosomal protein L30; Arabidopsis thaliana
ribosomal protein L24 homolog; Haloarcula marismortui ribosomal protein HL21/HL22; and Methanocaldococcus jannaschii (Methanococcus jannaschii) MJ1201. These proteins have 60 to 160 amino-acid residues.Ribosomal protein L24e/L24 is a ribosomal protein found in eukaryotes (L24) and in archaea (L24e, distinct from archaeal L24). L24e/L24 is located on the surface of the large subunit, adjacent to proteins L14 and L3, and near the translation factor binding site. L24e/L24 appears to play a role in the kinetics of peptide synthesis, and may be involved in interactions between the large and small subunits, either directly or through other factors. In mouse, a deletion mutation in L24 has been identified as the cause for the belly spot and tail (Bst) mutation that results in disrupted pigmentation, somitogenesis and retinal cell fate determination [
]. L24 may be an important protein in eukaryotic reproduction: in shrimp, L24 expression is elevated in the ovary, suggesting a role in oogenesis [], and in Arabidopsis, L24 has been proposed to have a specific function in gynoecium development [].The crystal structure of the L24e protein from Halobacterium marismortui (Haloarcula marismortui) has been determined [
,
]. The protein is composed of a single structural domain which forms an alpha/beta zinc-binding fold.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [,
].Ribosomal protein L5, ~180 amino acids in length, is one of the proteins from the large ribosomal subunit. In Escherichia coli, L5 is known to be involved in binding 5S RNA to the large ribosomal subunit. It belongs to a family of ribosomal proteins which, on the basis of sequence similarities [
,
,
], groups:Eubacterial L5.Algal chloroplast L5.Cyanelle L5.Archaebacterial L5.Mammalian L11.Tetrahymena thermophila L21.Dictyostelium discoideum (Slime mold) L5Saccharomyces cerevisiae (Baker's yeast) L16 (39A).Plant mitochondrial L5.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].Evidence suggests that, in prokaryotes, the peptidyl
transferase reaction is performed by the large subunit 23S rRNA, whereasproteins probably have a greater role in eukaryote ribosomes. Most of the
proteins lie close to, or on the surface of, the 30S subunit, arrangedperipherally around the rRNA [
]. The small subunit ribosomal proteins canbe categorised as primary binding proteins, which bind directly and
independently to 16S rRNA; secondary binding proteins, which display nospecific affinity for 16S rRNA, but its assembly is contingent upon the
presence of one or more primary binding proteins; and tertiary bindingproteins, which require the presence of one or more secondary binding
proteins and sometimes other tertiary binding proteins.The small ribosomal subunit protein S21 contains 55-70 amino acid residues,
and has only been found in eubacteria to date, though it has been reported that plant chloroplasts and mammalian mitochondria contain ribosomal subunit protein S21. Experimental evidence hasrevealed that S21 is well exposed on the surface of the Escherichia coli
ribosome [], and is one of the 'split proteins': these are a discrete groupthat are selectively removed from 30S subunits under low salt conditions
and are required for the formation of activated 30S reconstitutionintermediate (RI*) particles.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].This family includes ribosomal L4/L1 from eukaryotes and plants and L4 from bacteria. L4 from yeast has been shown to bind rRNA [
]. These proteins have 246 (plant) to 427 (human) amino acids.
Ribosomal protein L22 (L17 in eukaryotes) is a core protein of the large ribosomal subunit. It is the only ribosomal protein that interacts with all six domains of 23S rRNA, and is one of the proteins important for directing the proper folding and stabilizing the conformation of 23S rRNA. L22 is the largest protein contributor to the surface of the polypeptide exit channel, the tunnel through which the polypeptide product passes. L22 is also one of six proteins located at the putative translocon binding site on the exterior surface of the ribosome [
,
].Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].A number of eukaryotic and archaebacterial large subunit ribosomal proteins can be grouped on the basis of sequence similarities.
These proteins are very basic. At about 50 residues long, they are the smallestproteins of eukaryotic-type ribosomes.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].This entry represents the L40 ribosomal domain from both archaea and eukaryotes. In eukaryotes, L40 is fused to ubiquitin moieties, and this fusion protein is known as UBL40 [
,
]. Specific endopeptidases cleave these precursor molecules to release ubiquitin moieties []. UBL40 plays important roles in gametogenesis [,
]. This fusion may also have a pre-cleavage function in ribosome assembly [].
This entry contains cytosolic Fe-S cluster assembling factors NBP35 and CFD1. The NBP35-CFD1 heterotetramer forms a Fe-S scaffold complex, mediating the de novo assembly of an Fe-S cluster and its transfer to target apoproteins. Nucleotide binding and hydrolysis seems to be critical for loading of Fe-S clusters onto CFD1 and NBP35 [
,
,
]. In higher eukaryotes NBP35 and CFD1 are known as NUBP1 and NUBP2, and NUBP1 is also involved in iron regulation [].Bacterial homologues ApbC and MRP (Multiple Resistance and pH adaptation in E. coli) have been shown to contain an ATP-binding domain at the N terminus and have ATPase activity. MRP is a membrane-spanning protein and functions as a Na+/H+ antiporter [,
]. Archaeal homologues function as iron-sulfur cluster carriers [].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].The L21E family contains proteins from a number of eukaryotic
and archaebacterial organisms which include mammalian L2, Entamoeba histolytica L21, Caenorhabditis elegans L21 (C14B9.7), Saccharomyces cerevisiae (Baker's yeast) L21E (URP1) and Haloarcula marismortui HL31.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].Members of this family are large subunit ribosomal proteins which are found in the Eukaryota and Archaea. These proteins have 115 to 187 amino-acid residues. The family consists of:
Vertebrate L18 (known as L14 in Xenopus) []
Plant L18Yeast L18 (Rp28)Haloarcula marismortui (Halobacterium marismortui) HL29Sulfolobus acidocaldarius HL29e
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].A number of eukaryotic ribosomal proteins can be grouped on the basis of sequence similarities. One
of these families, the S26E family, includes mammalian S26 []; Octopus S26 [];Drosophila S26 (DS31) [
]; plant cytoplasmic S26; and fungal S26 []. S26 may be involved in the attachment of eIF3 and poly (U) []. Disruption of RPS26, the gene encoding a homologue of ribosomal protein small subunit S26 in yeast (S. cerevisiae), resulted in the formation of micro-colonies, suggesting that it is important for the normal cell growth of S. cerevisiae [].
This entry represents spermatogenesis-associated protein 20 (also known as sperm-specific protein 411 (Ssp411)), which is a testis-specific protein that contains a thioredoxin-like domain, and may play a role in fertility regulation [
]. Other family members include a number of uncharacterised proteins with thioredoxin domains.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].This family represents eukaryotic ribosomal protein S15 and its archaeal equivalent. It excludes bacterial and organellar ribosomal protein S19. The nomenclature for the archaeal members is unresolved and given variously as S19 (after the more distant bacterial homologues) or S15.
Ubiquitin-fold proteins are an important class of eukaryotic post-translational modifiers [
,
]. They are generally short proteins (less than 200 amino acids) which contain the core β-grasp fold (also known as the ubiquitin fold) and a C-terminal extension which enables their attachment to other proteins through the terminal carboxyl group. Protein-conjugated ubiquitins have been implicated an a wide variety of cellular process including proteolysis, DNA repair, transcription and autophagy Some ubiquitin-like proteins are not conjugated to proteins, but are instead anchored to the cell membrane by attachment to phospholipids or isoprenes. The functions of these membrane-associated proteins are not generally well understood. In the case of isoprene attachemnet, the prenyl group may also play a role in enhancing protein-protein interactions.This entry represents a group of membrane-associated ubiquitin-fold proteins found in plants and animals [
]. In Arabidopsis, membrane-anchored ubiquitin-fold (MUB) proteins recruit and dock specific E2s to the plasma membrane. They appear to interact noncovalently with an E2 surface opposite the active site that forms a covalent linkage with Ub []. The animal homologues of MUBs, also known as UBL3, have also been identified as ubiquitin-like proteins [].
This family includes the GTP-binding protein BipA or TypA (Tyrosine phosphorylated protein A (TypA), also known as 50S ribosomal subunit assembly factor BipA) from bacteria and its homologue from Arabidopsis (putative elongation factor TypA-like SVR3). BipA is a 50S ribosomal subunit assembly protein with GTPase activity, required for 50S subunit assembly at low temperatures, also functions as a translation factor that is required specifically for the expression of the transcriptional modulator Fis. BipA binds the 70S ribosome at a site that coincides with that of EF-G and has a GTPase activity that is sensitive to high GDP:GTP ratios and is stimulated by 70S ribosomes programmed with mRNA and aminoacylated tRNAs [
,
]. The growth rate-dependent induction of BipA allows the efficient expression of Fis, thereby modulating a range of downstream processes, including DNA metabolism and type III secretion. This GTPase impacts interactions between enteropathogenic E.coli (EPEC) and epithelial cells and also has an effect on motility []. It appears to be involved in the regulation of several processes important for infection, including rearrangements of the cytoskeleton of the host, bacterial resistance to host defence peptides, flagellum-mediated cell motility, and expression of K5 capsular genes [,
].TypA-like SVR3 is a putative chloroplastic elongation factor involved in response to chilling stress. It is required for proper chloroplast rRNA processing and/or translation at low temperature [] and it is also involved in plastid protein homeostasis [].
Atg101 is a critical autophagy factor that functions together with ULK, Atg13 and FIP200 [
,
]. In fission yeasts, it has a role in meiosis and sporulation [].
This entry represents a group of plant multispanning transmembrane proteins that are regulated by cold. This family can be classified into two groups: the cold-regulated (COR)413-plasma membrane and COR413-thylakoid membrane groups. Proteins in this family have a highly conserved phosphorylation site and a glycosylphosphatidylinositol-anchoring site at the C-terminal end [
,
].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [,
].Ribosomal protein S8 is one of the proteins from the small ribosomal subunit. In Escherichia coli, S8 is known to bind
directly to 16S ribosomal RNA. It belongs to a family of ribosomal proteins which, on the basis of sequencesimilarities, groups eubacterial, algal and plant chloroplast, cyanelle, archaebacterial and
Marchantia polymorpha mitochondrial S8; mammalian and plant S15A; and yeast S22 (S24) ribosomal proteins.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].The genomic structure and sequence of the human ribosomal protein L7a has been determined [
]. The gene contains 8 exons and 7 introns, encompassing 3179 bp. The human gene resembles other mammalian ribosomal protein genes in so far as it contains a short first exon, a short 5' untranslated leader and its transcriptional start sites at C residues embedded in a poly-pyrimidine tract [].The sequence of a gene for ribosomal protein L4 of Saccharomyces cerevisiae (Baker's yeast) has also been determined, which, unlike most of its other ribosomal protein genes, has no intron [
]. The single open reading frame is highly similar to mammalian ribosomal protein L7a.There appear to be two genes for L4, both of which are active [
]. Yeast cells containing a disruption of the L4-1 gene form smaller colonies than either wild-type or disrupted L4-2 strains. Disruption of both L4 genes is lethal, probably resulting from an inability of the organism to produce functional ribosomes [].Several other ribosomal proteins have been found to share sequence similarity with L7a, including yeast NHP2 [
], Bacillus subtilis hypothetical protein ylxQ, Haloarcula marismortui (Halobacterium marismortui) Hs6, and Methanocaldococcus jannaschii MJ1203.This InterPro entry focus on regions that characterise the ribosomal L7A proteins but distinguish them from the rest of the HMG-like family.
Members of this family are integral membrane proteins, that
are found to increase tolerance to divalent metal ions suchas cadmium, zinc, and cobalt. These proteins are considered to
be efflux pumps that remove these ions from cells [,
], however others are implicated in ion uptake []. Thefamily has six predicted transmembrane domains. Members of the family are variable
in length because of variably sized inserts, often containing low-complexity sequence.
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].The ribosomal protein family L20, from the large (50S) subunit, contains members from eubacteria, as well as their mitochondrial and plastid homologs. L20 is an assembly protein, required for the first in vitro reconstitution step of the 50S ribosomal subunit, but does not seem to be essential for ribosome activity. L20 has been shown to partially unfold in the absence of RNA, in regions corresponding to the RNA-binding sites. L20 represses the translation of its own mRNA via specific binding to two distinct mRNA sites, in a manner similar to the L20 interaction with 23S ribosomal RNA [
,
,
,
,
,
,
].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].Ribosomal protein S5 is one of the proteins from the small ribosomal subunit, and is a protein of 166 to 254 amino acid residues. In Escherichia coli, S5 is known to be important in the assembly and function of the 30S ribosomal subunit. Mutations in S5 have been shown to increase translational
error frequencies. It belongs to a family of ribosomal proteins which, on the basis of sequence similarities [], groups bacterial, cyanelle, red algal chloroplast, archaeal and fungal mitochondrial S5; mammalian, Caenorhabditis elegans, Drosophila and plant S2; and yeast 40S ribosomal protein S2 (also known as SUP44).
Microtubule-associated protein 70 (MAP70) are plant-specific proteins that interact with microtubules. In Arabidopsis thaliana, there are five MAP70 genes (MAP70-1/2/3/4/5). MAP70-1 associates with MAP70-5 and is essential for the normal banding pattern of secondary cell wall and for the proper development of xylem tracheary elements and wood formation [
,
].
The eukaryotic defective in cullin neddylation (DCN) protein family, contributes to neddylation of cullin components of SCF-type E3 ubiquitin ligase complexes. These multi-protein complexes are required for polyubiquitination and subsequent degradation of target proteins by the 26S proteasome [
,
,
]. Proteins in the DCN family include:Yeast DCN1.Vertebrate DCN1-like protein 1-5.Plant Defective in cullin neddylation protein AAR3 [
].DCN family proteins all contain a Potentiating neddylation (PONY) domain (
), contains a cullin-binding surface within its C-terminal region and is sufficient to promote neddylation [
,
]. The N-terminal region of the protein often contains a UBA-like domain.
This entry consists of the human Hus1 protein and budding yeast Mec3. They are components of the checkpoint clamp complex involved in the surveillance mechanism that allows the DNA repair pathways to act to restore the integrity of the DNA prior to DNA synthesis or separation of the replicated chromosomes [
,
]. Hus1, Rad1, and Rad9 (which share homology with Mec1, Rad17, Ddc1 in budding yeast) are three evolutionarily conserved proteins required for checkpoint control. These proteins are known to form a stable complex. Structurally, the Ddc1-Mec3-Rad17 complex is similar to the PCNA complex, which forms trimeric ring-shaped clamps. Ddc1-Mec3-Rad17 plays a role in checkpoint activation that permits DNA-repair pathways to prevent cell cycle progression in response to DNA damage and replication stress [,
].
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [
,
]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits. Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [
,
].A number of eukaryotic and archaebacterial ribosomal proteins can be grouped on the basis of sequence similarities. Examples are:
Mammalian S28 [
]
Plant S28 [
]
Fungi S33 [
]
Archaebacterial S28e.These proteins have from 64 to 78 amino acids and a highly conserved C-terminal region.S1-like RNA-binding domains are found in a wide variety of RNA-associated proteins. S28E protein is a component of the 30S ribosomal subunit. S28E is highly conserved among archaea and eukaryotes. S28E may control precursor RNA splicing and turnover in mRNA maturation process but its function in the ribosome is largely unknown. The structure contains an OB-fold found in many oligosaccharide and nucleic acid binding proteins. This implies that S28E might be involved in protein synthesis [
,
,
].
