Chloroplast function requires the import of nuclear encoded proteins from the cytoplasm across the chloroplast double membrane. This is accompished by two protein complexes, the Toc complex located at the outer membrane and the Tic complex loacted at the inner membrane [
]. The Toc complex recognises specific proteins by a cleavable N-terminal sequence and is primarily responsible for translocation through the outer membrane, while the Tic complex translocates the protein through the inner membrane.This entry represents Tic20, a core member of the Tic complex. This protein is deeply embedded in the inner envelope membrane and is thought to function as a protein conducting component of the Tic complex [
].
There is currently no experimental data for members of this group or their homologues, nor do they exhibit features indicative of any function. Members of this entry are mainly found in proteobacteria.
S14 is one of the proteins from the small ribosomal subunit.
In Escherichia coli, S14 is known to be required for the assembly of 30S particlesand may also be responsible for determining the conformation of 16S rRNA at the A site.
It belongs to a family of ribosomal proteins [] thatinclude bacterial, algal and plant chloroplast S14, yeast mitochondrial MRP2, cyanelle S14, archaebacteria Methanococcus vannielii S14, as well as yeast mitochondrial MRP2, yeast YS29A/B, and mammalian S29.
Ribosomal RNA processing protein 8 (Rrp8) is a nucleolar Rossman-fold like methyltransferase. In yeast, it is involved in pre-rRNA cleavage at site A2 [
] and is responsible for a base methylation of the 25S rRNA []. In humans it is also known as nucleomethylin (NML), and it is important for mediating the assembly of the energy-dependent nucleolar silencing complex (eNoSC), which regulates rRNA transcription in response to glucose deprivation []. NML represses rDNA transcription by promoting H3K9 methylation and establishing heterochromatin across the rDNA [].
The expression of early nodulin (ENOD) genes has been well characterised in several legume species. Based on their biochemical attributes and expression
patterns, they are postulated to have roles in cell structure, in the control of nodule ontogeny by the degradation of Nod factor, and in carbon metabolism [].
This entry represents the regulator of ribonuclease E activity A (RraA). These proteins contain a swivelling 3-layer beta/beta/alpha domain that appears to be mobile in most multi-domain proteins known to contain it. These proteins are structurally similar, and may have distant homology, to the phosphohistidine domain of pyruvate phosphate dikinase. The RraA fold is an ancient platform that has been adapted for a wide range of functions. RraA had been identified as a putative demethylmenaquinone methyltransferase and was annotated as MenG, but further analysis showed that RraA lacked the structural motifs usually required for methylases [
]. The Escherichia coli protein regulator RraA acts as a trans-acting modulator of RNA turnover, binding essential endonuclease RNase E and inhibiting RNA processing [
]. RNase E forms the core of a large RNA-catalysis machine termed the degradosomes. RraA (and RraB) causes remodelling of degradosome composition, which is associated with alterations in RNA decay and global transcript abundance and as such is a bacterial mechanism for the regulation of RNA cleavage.This fold is also found in 4-hydroxy-4-methyl-2-oxoglutarate aldolase, also known as RraA-like protein [
] and at the C terminus of the DlpA protein .
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.This entry represents a conserved region located in the C-terminal half of these 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 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.
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 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 specific affinity 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 entry represents a short conserved sequence region located towards the C terminus of S17.
This represents the mitotic checkpoint serine/threonine-protein kinase Bub1. Saccharomyces cerevisiae Bub1 has a paralogue, Mad3, which is also included in this entry. Bub1 forms a complex with Mad1 and Bub3 that is crucial for preventing cell cycle progression into anaphase in the presence of spindle damage [
], while Mad3 is a component of the spindle-assembly complex consisting of Mad2, Mad3, Bub3 and Cdc20 []. Mad3 contains a D-box and two KEN- boxes, which function together to mediate Cdc20-Mad3 interaction. Mad3 and an anaphase-promoting complex (APC) substrate, Hsl1, compete for Cdc20 binding in a D-box- and KEN-box-dependent manner [].Similar to its yeast homologues, human Bub1 is a critical component of the mitotic checkpoint that delays the onset of anaphase until all chromosomes have established bipolar attachment to the microtubules. In interphase cells it localises to centrosomes and suppresses centrosome amplification via regulating Plk1 activity [
]. Mutations in the human Bub1 gene have been linked to cancers [,
].
Spindle and kinetochore-associated protein 1 (SKA1) is a component of the SKA1 complex (consists of Ska1, Ska2, and Ska3/Rama1), a microtubule-binding subcomplex of the outer kinetochore that is essential for proper chromosome segregation [
]. It is required for timely anaphase onset during mitosis, when chromosomes undergo bipolar attachment on spindle microtubules leading to silencing of the spindle checkpoint []. The SKA1 complex is a direct component of the kinetochore-microtubule interface and directly associates with microtubules as oligomeric assemblies. The complex facilitates the processive movement of microspheres along a microtubule in a depolymerisation-coupled manner. SKA1 contains a microtubule-binding domain that interacts with tubulins using multiple contact sites that allow the Ska complex to bind microtubules in multiple modes [].
Phosphatidylinositol anchor biosynthesis protein PIGW/GWT1
Type:
Family
Description:
Glycosylphosphatidylinositol (GPI) is a conserved post-translational modification to anchor cell surface proteins to plasma membrane in eukaryotes. PIGW and the yeast homologue GWT1 are involved in the addition of the acyl-chain to inositol in an early step of GPI biosynthesis [
]. Mutations in PIGW are associated with West syndrome and hyperphosphatasia with mental retardation syndrome [].
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.
Telomerase activating protein Est1-like, N-terminal
Type:
Domain
Description:
Est1 is directly involved in telomere replication. It associates with telomerase and, during its interaction with CDC13, telomerase activity is promoted [
,
]. This entry also includes Est1 homologues, such as human EST1A (also known as SMG6), which is essential for the replication of chromosome termini [] and also plays a role in nonsense-mediated mRNA decay [,
].
No protein in this family has been characterized. This family is believed to be related to the PAP2 family, which includes phosphatases such as type 2 phosphatidic acid phosphatase (PAP2) and haloperoxidases.
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 anancient 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 [
].This entry represents the α-β domain found duplicated in ribosomal L6 proteins. This domain consists of two β-sheets and one α-helix packed around single core [
].
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 pattern identifies ribosomal protein L6, which is one of the proteins from the large ribosomal subunit. In Escherichia coli, L6 is known to bind directly to the 23S rRNA and is located at the aminoacyl-tRNA binding site of the peptidyltransferase centre.
It belongs to a family of ribosomal proteins, which on the basis of sequencesimilarities groups: bacterial, algal chloroplast, cyanelle, archaeal, Marchantia polymorpha mitochondrial L6, yeast mitochondrial YmL6 (gene MRPL6), mammalian, Drosophila melanogaster; plant and yeast L9 [
,
,
]. This signature finds the L6 proteins from most organisms, while plant L6 and the L9 proteins are also found in .
Sec-independent periplasmic protein translocase TatC
Type:
Family
Description:
Proteins encoded by the mttABC operon (formerly yigTUW), mediate a novel Sec-independent membrane targeting and translocation system in Escherichia coli that interacts with cofactor-containing redox proteins having a S/TRRXFLK "twin arginine"leader motif. This family contains the E. coli mttB gene (TATC) [
].A functional Tat system or Delta pH-dependent pathway requires three integral membrane proteins: TatA/Tha4, TatB/Hcf106 and TatC/cpTatC. The TatC protein is essential for the function of both pathways. It might be involved in twin-arginine signal peptide recognition, protein translocation and proton translocation. Sequence analysis predicts that TatC contains six transmembrane helices (TMHs), and experimental data confirmed that N and C termini of TatC or cpTatC are exposed to the cytoplasmic or stromal face of the membrane. The cytoplasmic N terminus and the first cytoplasmic loop region of the E. coli TatC protein are essential for protein export. At least two TatC molecules co-exist within each Tat translocon [
,
].
These sequences are a family of uncharacterised hypothetical proteins restricted to eukaryotes (
) represents a sequence from Nicotiana tabacum (Common tobacco) which is up regulated in response to TMV infection.
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.
This entry represents the conserved site of Ribosomal protein 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 signature pattern covers a conserved region containing many charged residues and located in the central section of these proteins.
Members of this eukaryotic family are part of the group II chaperonin complex called CCT (chaperonin containing TCP-1 or Tailless Complex Polypeptide 1) or TRiC [
,
]. Chaperonins are involved in productive folding of proteins []. They share a common general morphology, a double toroid of 2 stacked rings. The archaeal equivalent group II chaperonin is often called the thermosome []. Both the thermosome and the TCP-1 family of proteins are weakly, but significantly [], related to the cpn60/groEL chaperonin family (see ).
The TCP-1 protein was first identified in mice where it is especially abundant in testis but present in all cell types. It has since been found and characterised in many other animal species, as well as in yeast, plants and protists. The TCP1 complex has a double-ring structure with central cavities where protein folding takes place [
]. TCP-1 is a highly conserved protein of about 60kDa (556 to 560 residues) which participates in a hetero-oligomeric 900kDa double-torus shaped particle [] with 6 to 8 other different, but homologous, subunits []. These subunits, the chaperonin containing TCP-1 (CCT) subunit beta, gamma, delta, epsilon, zeta and eta are evolutionary related to TCP-1 itself [,
]. Non-native proteins are sequestered inside the central cavity and folding is promoted by using energy derived from ATP hydrolysis [,
,
]. The CCT is known to act as a molecular chaperone for tubulin, actin and probably some other proteins [,
].This family consists exclusively of the CCT beta chain (part of a paralogous family) from animals, plants, fungi, and other eukaryotes.
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.
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.This entry represents a conserved sequence region found towards the N terminus of
ribosomal protein L24e. It is also found in ribosomal protein L24-like, an essential protein with similarity to Rpl24Ap and Rpl24Bp, which is associated with pre-60S ribosomal subunits and required for ribosomal large subunit biogenesis [,
].
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.This entry represents a short conserved sequence found in the N-terminal region of these 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 [
,
].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.This superfamily represents the L5 structural domain, which forms a 2 layer, mainly antiparallel β-sheet.
This family of transmembrane proteins are functionally uncharacterised. This protein is found in eukaryotes. Proteins in this family are typically between 427 to 453 amino acids in length.
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 [
,
].This superfamily represents a domain found in ribosomal protein L4. Its structure consists of three layers (alpha/beta/alpha) with parallel β-sheet of four strands.
This family of proteins is functionally uncharacterised. This protein is found in bacteria and eukaryotes. Proteins in this family are typically between 149 to 199 amino acids in length.
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 L22 is one of the proteins from the large ribosomal subunit.
In Escherichia coli, L22 is known to bind 23S rRNA []. It belongs to a family ofribosomal proteins which includes: bacterial L22; algal and plant chloroplast L22
(in legumes L22 is encoded in the nucleus instead of the chloroplast); cyanelle L22;archaebacterial L22; mammalian L17; plant L17 and yeast YL17.
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.This superfamily represents the structural domain found in ribosomal proteins belonging to the L39e family, which includes eukaryotic and archaeal 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 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.This entry represents a conserved region in the C-terminal section of these proteins.
This plant-specific family of proteins are defined by an uncharacterised region 57 residues in length. It is found toward the N terminus of most proteins that contain it. Examples include at least several proteins from Arabidopsis thaliana (Mouse-ear cress) and Oryza sativa (Rice). The function of the proteins are unknown.
Rfa3 (also known as RPA14) is a component of the replication protein A (RPA) complex, which binds to and removes secondary structure from ssDNA. The RPA complex is involved in DNA replication, repair, and recombination [
].
Chromodomain-helicase-DNA-binding protein 1-like, C-terminal domain
Type:
Domain
Description:
This entry represents a domain found at the C terminus of chromodomain-helicase-DNA-binding proteins, including Chromodomain-helicase-DNA-binding protein 1 from human (CHD1), an ATP-dependent chromatin-remodeling factor which acts as substrate recognition component of the transcription regulatory histone acetylation (HAT) complex SAGA. This protein functions to modulate the efficiency of pre-mRNA splicing in part through physical bridging of spliceosomal components to H3K4me3 [
,
]. This helical domain, which is also found in CHD1 helical C-terminal domain-containing protein 1 (also known as C17orf64) from mammals [], consists of five α-helices organised in a variant helical bundle topology. Its surface is positively charged and can bind dsDNA and nucleosomes, but its specific function remains unknown [].
This family consists of several hypothetical proteins from both cyanobacteria and plants. Members of this family are typically around 250 residues in length. The function of this family is unknown but the species distribution indicates that the family may be involved in photosynthesis.
This approximately 50-residue region is found in a number of sequences derived from hypothetical plant proteins. This region features a highly basic 5 amino-acid stretch towards its centre.
Baculoviral IAP repeat-containing protein 6 (BIRC6, also known as BRUCE) is an anti-apoptotic protein which can regulate cell death by controlling caspases and by acting as an E3 ubiquitin-protein ligase [
]. It has an unusual ubiquitin conjugation system in that it could combine in a single polypeptide, ubiquitin conjugating (E2) with ubiquitin ligase (E3) activity, forming a chimeric E2/E3 ubiquitin ligase []. It is crucial for normal vesicle targeting to the site of abscission, but also for the integrity of the midbody and the midbody ring, and its striking ubiquitin modification [].
Ribosomal protein L30 is one of the proteins from the large ribosomal subunit. L30 belongs to a family of ribosomal proteins which, on the basis of sequence similarities [
], groups bacteria and archaea L30, yeast mitochondrial L33, and Drosophila melanogaster, Dictyostelium discoideum (Slime mold), fungal and mammalian L7 ribosomal proteins. L30 from bacteria are small proteins of about 60 residues, those from archaea are proteins of about 150 residues, and eukaryotic L7 are proteins of about 250 to 270 residues.
This entry represents a conserved site of prokaryotic L30 and eukaryotic L7 ribosomal proteins. It is also found in ribosome biogenesis protein RLP7, a nucleolar protein that plays a critical role in processing of precursors to the large ribosomal subunit RNAs [
].
The P protein is part of the glycine decarboxylase multienzyme complex (GDC), also annotated as glycine cleavage system or glycine synthase. GDC consists of four proteins P, H, L and T [
]. The P protein () binds the alpha-amino group of glycine through its pyridoxal phosphate cofactor, carbon dioxide is released and the remaining methylamin moiety is then transferred to the lipoamide cofactor of the H protein. The reaction catalysed by this protein is:
Glycine + lipoylprotein = S-aminomethyldihydrolipoylprotein + CO2 The subunit composition of glycine cleavage system P proteins have been classified into two types. Those from eukaryotes and some of the P proteins from prokaryotes (e.g. Escherichia coli) are in the homodimeric form. The rest of those from prokaryotes are heterotetrameric, with two different subunits which, based on sequence similarities, correspond respectively to the N and C-terminal halves of the eukaryotic subunit [
].
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.
This entry includes Protein LOW PSII ACCUMULATION 1 (LPA1) from plants and some uncharacterised proteins from Cyanobacteria (blue-green algae). Arabidopsis LPA1 is a chaperone required for efficient photosystem II (PSII) assembly. It binds to psbA during de novo biogenesis of PSII [
].
This entry includes Ubiquitin fusion degradation protein Ufd1 from fungi and Ufd1-like proteins from animals and plants. Ufd1 is part of the Ufd1-Npl4 complex that functions as the substrate-recruiting cofactor for Cdc48 segregase. The Cdc48-Ufd1-Npl4 complex is involved in degradation of misfolded ER proteins [
]. The Ufd1-Npl4 complex has been found to recruit Cdc48 to ubiquitylated CMG (Cdc45-MCM-GINS) helicase at the end of chromosome replication, thereby driving the disassembly reaction [].In humans, Npl4-Ufd1 acts as a cofactor in reducing antiviral innate immune responses by facilitating proteasomal degradation of RIG-I (a viral RNA sensor) [
].
This family includes archaeal probable exosome complex RNA-binding protein 1, exosome complex component RRP40 and RRP4. They are subunits of either archaeal or eukaryotic exosome complex. Exosome is a complex of 3' -->5' exoribonucleases that play a major role in diverse RNA processing and degradation pathways. The eukaryotic exosome complex contains 9 proteins. Six RNase PH domain containing proteins (Rrp41, Rrp42, Rrp43, Rrp45, Rrp46, and Mtr3) form a catalytic ring, three RNA binding domain containing proteins (Rrp4,Rrp40, and Csl4) bind on top of the ring [].In the archaeal exosome, the hexameric ring is formed by three dimers of the orthologs of Rrp41 and Rrp42 and degrades poly(A) RNA phosphorolytically. Three proteins with RNA binding domains (orthologues of Rrp4 or Csl4) bind to the ring and influences degradation of a short poly(A) RNA substrate by the hexameric ring [
,
]. In this entry, RRP40 and RRP4 are both non-catalytic components of the RNA exosome complex [
,
]. Exosome complex RNA-binding protein 1 contains a S1 and a KH domain and is the archaeal ortholog of eukaryotic Rrp4 [].
The bacterial ribosomal protein L25 is bound to 5S rRNA along with L5 and L18, forming a separate domain of the ribosome [
]. The solution structure of protein L25 uncomplexed with RNA shows two significantly disordered loops and a closed β-barrel domain with a complex topology that has significant structural similarities to the N-terminal domain of the Thermus thermophilus ribosomal protein TL5, to the general stress protein CTC, and to the C-terminal anticodon-binding domain of Escherichia coli glutaminyl-tRNA synthetase (GlnRS) [,
]. GlnRS contains a duplication consisting of two L25-like β-barrels domains with the swapping of N-terminal strands.This entry represents a domain with a mainly β-strand structure found in ribosomal L25-like proteins.
Ribosomal protein L25/Gln-tRNA synthetase, N-terminal
Type:
Homologous_superfamily
Description:
The bacterial ribosomal protein L25 is bound to 5S rRNA along with L5 and L18, forming a separate domain of the ribosome [
]. The solution structure of protein L25 uncomplexed with RNA shows two significantly disordered loops and a closed β-barrel domain with a complex topology that has significant structural similarities to the N-terminal domain of the Thermus thermophilus ribosomal protein TL5, to the general stress protein CTC, and to the C-terminal anticodon-binding domain of Escherichia coli glutaminyl-tRNA synthetase (GlnRS) [,
]. GlnRS contains a duplication consisting of two L25-like β-barrels domains with the swapping of N-terminal strands.This superfamily represents the N-terminal domain, which has a β-barrel structure.
The adaptor protein complexes mediate both the recruitment of clathrin to membranes and the recognition of sorting signals within the cytosolic tails of transmembrane cargo molecules [
]. Adaptor protein complex 1 (AP-1) is a heterotetramer composed of two large adaptins (gamma-type subunit AP1G1 and beta-type subunit AP1B1), a medium adaptin (mu-type subunit AP1M1 or AP1M2) and a small adaptin (sigma-type subunit AP1S1 or AP1S2 or AP1S3). Subunits of clathrin-associated adaptor protein complex 1 play a role in protein sorting in the late-Golgi/trans-Golgi network (TGN) and/or in endosomes.This group represents an adaptor protein complex, sigma subunit.
Members of this eukaryotic family are part of the group II chaperonin complex called CCT (chaperonin containing TCP-1 or Tailless Complex Polypeptide 1) or TRiC [
,
]. Chaperonins are involved in productive folding of proteins []. They share a common general morphology, a double toroid of 2 stacked rings. The archaeal equivalent group II chaperonin is often called the thermosome []. Both the thermosome and the TCP-1 family of proteins are weakly, but significantly [], related to the cpn60/groEL chaperonin family (see ).
The TCP-1 protein was first identified in mice where it is especially abundant in testis but present in all cell types. It has since been found and characterised in many other animal species, as well as in yeast, plants and protists. The TCP1 complex has a double-ring structure with central cavities where protein folding takes place [
]. TCP-1 is a highly conserved protein of about 60kDa (556 to 560 residues) which participates in a hetero-oligomeric 900kDa double-torus shaped particle [] with 6 to 8 other different, but homologous, subunits []. These subunits, the chaperonin containing TCP-1 (CCT) subunit beta, gamma, delta, epsilon, zeta and eta are evolutionary related to TCP-1 itself [,
]. Non-native proteins are sequestered inside the central cavity and folding is promoted by using energy derived from ATP hydrolysis [,
,
]. The CCT is known to act as a molecular chaperone for tubulin, actin and probably some other proteins [,
].This family consists exclusively of the CCT eta chain (part of a paralogous family) from animals, plants, fungi, and other eukaryotes.
Nucleolar complex-associated protein 3, N-terminal
Type:
Domain
Description:
This entry represents the N-terminal domain of the nucleolar complex-associated protein (Noc3), which is conserved in eukaryotes and plays essential roles in replication and rRNA processing in Saccharomyces cerevisiae [
].
This entry represents the N-terminal domain of proteins that are highly conserved in species ranging from archaea to vertebrates and plants [
], including several Shwachman-Bodian-Diamond syndrome (SBDS, OMIM 260400) proteins from both mouse and humans. Shwachman-Diamond syndrome is an autosomal recessive disorder with clinical features that include pancreatic exocrine insufficiency, haematological dysfunction and skeletal abnormalities. It is characterised by bone marrow failure and leukemia predisposition.Members of this entry play a role in RNA metabolism [
,
]. In yeast, SBDS orthologue SDO1 is involved in the biogenesis of the 60S ribosomal subunit and translational activation of ribosomes. Together with the EF-2-like GTPase RIA1 (EfI1), it triggers the GTP-dependent release of TIF6 from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly and facilitating TIF6 recycling to the nucleus, where it is required for 60S rRNA processing and nuclear export. This data links defective late 60S subunit maturation to an inherited bone marrow failure syndrome associated with leukemia predisposition [].The SBDS protein is composed of three domains. The N-terminal domain (FYSH, represented in this entry) is the most frequent target for disease mutations and contains a novel mixed α/β-fold, the central domain (
) consists of a three-helical bundle and the C-terminal domain (
) has a ferredoxin-like fold [
,
].
In most eukaryotes, their chromosome ends are composed of a single stranded overhang that contains GT-rich repeats and are bound by telomerase ribonucleoproteins (RNPs).This entry represents a group of telomere binding proteins, including the protection of telomeres protein 1 (POT1) from humans/fission yeast/plants, the telomere end binding proteins (TEBP) alpha from the hypotrichous ciliate Oxytricha nova and Cdc13 from Saccharomyces cerevisiae. They are ribonucleoproteins (RNPs) that play an important role in telomere maintenance, but the precise roles played in end protection and telomere length regulation seem to vary considerably between organisms [
,
]. In fission yeast, POT1 prevents access of telomerase to the 3'-end and protects against exonucleolytic degradation [
]. However, in humans, POT1 might function predominantly in telomere length regulation rather than in the protection of telomeres []. In Arabidopsis, there are several POT-like proteins, including POT1a, POT1b and POT1c []. POT1a and POT1b are components of telomerase rather than telomere capping components []. In Saccharomyces cerevisiae an OB-fold containing protein called Cdc13 plays a similar role as POT1, such as single-stranded G-rich telomeric DNA binding and telomere maintenance [
,
].
Members of this eukaryotic family are part of the group II chaperonin complex called CCT (chaperonin containing TCP-1 or Tailless Complex Polypeptide 1) or TRiC [
,
]. Chaperonins are involved in productive folding of proteins []. They share a common general morphology, a double toroid of 2 stacked rings. The archaeal equivalent group II chaperonin is often called the thermosome []. Both the thermosome and the TCP-1 family of proteins are weakly, but significantly [], related to the cpn60/groEL chaperonin family (see ).
The TCP-1 protein was first identified in mice where it is especially abundant in testis but present in all cell types. It has since been found and characterised in many other animal species, as well as in yeast, plants and protists. The TCP1 complex has a double-ring structure with central cavities where protein folding takes place [
]. TCP-1 is a highly conserved protein of about 60kDa (556 to 560 residues) which participates in a hetero-oligomeric 900kDa double-torus shaped particle [] with 6 to 8 other different, but homologous, subunits []. These subunits, the chaperonin containing TCP-1 (CCT) subunit beta, gamma, delta, epsilon, zeta and eta are evolutionary related to TCP-1 itself [,
]. Non-native proteins are sequestered inside the central cavity and folding is promoted by using energy derived from ATP hydrolysis [,
,
]. The CCT is known to act as a molecular chaperone for tubulin, actin and probably some other proteins [,
].This family consists exclusively of the CCT delta chain (part of a paralogous family) from animals, plants, fungi, and other eukaryotes.
This family consists of Raptor (regulatory associated protein of TOR) and its orthologs which includes Kog1p of Saccharomyces cerevisiae (Baker's yeast), a highly conserved 150kDa TOR-binding protein [
,
,
]. The target-of-rapamycin (TOR) proteins are protein kinases that were first identified in S. cerevisiae through mutants that conferred resistance to growth inhibition induced by the immunosuppressive macrolide rapamycin [].All Raptor orthologs contain a unique conserved region in their N-terminal half (raptor N-terminal conserved, also called the RNC domain) followed by three HEAT (huntingtin, elongation factor 3, A subunit of protein phosphatase 2A and TOR1) repeats and seven WD-40 repeats near the C terminus. Research on mammalian Raptor suggests that its association with mTOR promotes the phosphorylation of downstream effectors in nutrient-stimulated cells [,
]. In concordance with these observations, the binding of TOR to Raptor or to Kog1p [] is necessary for TOR signalling in vivo in Caenorhabditis elegans and S. cerevisiae [,
].The RNC domain consists of 3 blocks with at least 67 to 79% sequence similarity and is predicted to have a high propensity to form alpha helices. The RNC domain is characterised by the presence of invariant catalytic Cys-His dyad, which is structurally and evolutionarily related to known caspases, suggesting that the raptor proteins may have protease activity [].
A number of eukaryotic and archaebacterial ribosomal proteins can be grouped
on the basis of sequence similarities. One of these families consists of:Mammalian S28 [
].Plant S28 [
].Fungi S33 [
].Archaebacterial S28e.These proteins have from 64 to 78 amino acids. This entry represents a highly conserved nonapeptide from the C-terminal extremity of these proteins.NOTE: This entry matches
, which is a translation initiation factor IF-2. This is a false positive.
Replication factor-a protein 1 (RPA1) forms a multiprotein complex with RPA2 and RPA3 that binds single-stranded DNA and functions in the recognition of DNA damage for nucleotide excision repair. The complex binds to single-stranded DNA sequences participating in DNA replication in addition to those mediating transcriptional repression and activation, and stimulates the activity of cognate strand exchange protein Sep1. It cooperates with T-AG and DNA topoisomerase I to unwind template DNA containing the Simian Virus 40 origin of replication [
].
Rfa1 (also known as RPA70) is a component of the replication protein A (RPA) complex, which binds to and removes secondary structure from ssDNA. The RPA complex is involved in DNA replication, repair, and recombination [
].
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 L13e is widely found in vertebrates [
], Drosophila melanogaster, plants, yeast, amongst others.
Phosphatidylinositol-glycan biosynthesis class S protein
Type:
Family
Description:
Phosphatidylinositol-glycan biosynthesis class S protein (PIG-S, also known as Gpi17 in budding yeasts) is one of several key, core components of the glycosylphosphatidylinositol (GPI) trans-amidase complex that adds GPIs to newly synthesized proteins [
]. Mammalian GPI transamidase consists of at least five components: Gaa1, Gpi8, PIG-S, PIG-T, and PIG-U, all five of which are required for its function. It is possible that Gaa1, Gpi8, PIG-S, and PIG-T form a tightly associated core that is only weakly associated with PIG-U [].
Protein translocase complex, SecE/Sec61-gamma subunit
Type:
Family
Description:
Secretion across the inner membrane in some Gram-negative bacteria occurs via the preprotein translocase
pathway. Proteins are produced in the cytoplasm as precursors, and require a chaperone subunit to direct them tothe translocase component [
]. From there, the mature proteins are either targeted to the outermembrane, or remain as periplasmic proteins. The translocase protein subunits are encoded on the bacterial
chromosome.The translocase itself comprises 7 proteins, including a chaperone protein (SecB), an ATPase (SecA), an integral
membrane complex (SecCY, SecE and SecG), and two additional membrane proteins that promote the release ofthe mature peptide into the periplasm (SecD and SecF) [
]. The chaperone protein SecB [] is a highly acidic homotetrameric protein that exists as a "dimer of dimers"in the bacterial cytoplasm.
SecB maintains preproteins in an unfolded state after translation, and targets these to the peripheral membraneprotein ATPase SecA for secretion [
]. SecE, part of the main SecYEG translocase complex, is ~106 residues in length, and spans the
inner membrane of the Gram-negative bacterial envelope. Together withSecY and SecG, SecE forms a multimeric channel through which preproteins
are translocated, using both proton motive forces and ATP-driven secretion. The latter is mediated by SecA. In eukaryotes, the evolutionary related protein sec61-gamma plays a role in protein translocation through the endoplasmic reticulum; it is part of a trimeric complex that also consist of sec61-alpha and beta [
]. Both secE and sec61-gamma are small proteins of about 60 to 90 amino acids that contain a single transmembrane region at their C-terminal extremity (Escherichia coli secE is an exception, in that it possess an extra N-terminal segment of 60 residues that contains two additional transmembrane domains) [].
snRNA-activating protein complex 50kDa subunit (SNAP50), also known as subunit 3, is part of the snRNA-activating protein complex which activates RNA polymerases II and III [
]. It contains a cysteine-histidine cluster with two possible zinc finger motifs.
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.
Prokaryotes and eukaryotes respond to heat shock and other forms of
environmental stress by inducing synthesis of heat-shock proteins (hsp) []. The 90kDa heat shock protein, Hsp90, is one of the most abundant proteins in eukaryotic cells, comprising 1-2% of cellular proteins under non-stress conditions []. Its contribution to various cellular processes including signal transduction, protein folding, protein degradation and morphological evolution has been extensively studied [,
]. The full functional activity of Hsp90 is gained in concert with other co-chaperones, playing an important role in the folding of newly synthesised proteins and stabilisation and refolding of denatured proteins after stress. Apart from its co-chaperones, Hsp90 binds to an array of client proteins, where the co-chaperone requirement varies and depends on the actual client. The
sequences of hsp90s show a distinctive domain structure, with a highly-conserved N-terminal domain separated from a conserved, acidic C-terminaldomain by a highly-acidic, flexible linker region.
Molecular chaperones, or heat shock proteins (Hsps) are ubiquitous proteins that act to maintain proper protein folding within the cell [
]. They assist in the folding of nascent polypeptide chains, and are also involved in the re-folding of denatured proteins following proteotoxic stress. As their name implies, the heat shock proteins were first identified as proteins that were up-regulated under conditions of elevated temperature. However, subsequent studies have shown that increased Hsp expression is induced by a variety of cellular stresses, including oxidative stress and inflammation. Five major Hsp families have been determined, and are categorized according to their molecular size (Hsp100, Hsp90, Hsp70, Hsp60, and the small Hsps). Hsps are involved in a variety of cellular processes that are ATP-dependent. These include: prevention of protein aggregation, protein degradation, protein trafficking, and maintenance of signalling proteins in a conformation that permits activation.
Hsp90 chaperones are unique in their ability to regulate a specific subset of cellular signalling proteins that have been implicated in disease processes, including intracellular protein kinases, steroid hormone receptors, and growth factor receptors [
].
Within mitochondria and bacteria, a family of related proteins is involved
in the assembly of periplasmic c-type cytochromes: these include CycK [], CcmF [,
], NrfE [] and CcbS []. These proteins may play a role in guidance of apocytochromes and haem groups for their covalent linkage
by the cytochrome-c-haem lyase. Members of the family are probably integralmembrane proteins, with up to 16 predicted transmembrane (TM) helices.
The gene products of the hel and ccl loci have been shown to be required
specifically for the biogenesis of c-type cytochromes in the Gram-negativephotosynthetic bacterium Rhodobacter capsulatus [
]. Genetic and molecularanalyses show that the hel locus contains at least 4 genes, helA, helB, helC
and orf52. HelA is similar to the ABC transporters and helA, helB, and
helC are proposed to encode an export complex []. It is believed that thehel-encoded proteins are required for the export of haem to the periplasm,
where it is subsequently ligated to the c-type apocytochromes []. However,while CcmB and CcmC have the potential to interact with CcmA, the 3 gene
products probably associating to form a complex with (CcmA)2-CcmB-CcmCstoichiometry, the substrate for the putative CcmABC-transporter is probably
neither haem nor c-type apocytochromes []. Hydropathy analysis suggeststhe presence of 6 TM domains.
Ribosomal protein L1 is the largest protein from the large ribosomal subunit. The L1 protein contains two domains: 2-layer alpha/beta domain and a 3-layer alpha/beta domain (interrupts the first domain). This entry represents the 3-layer domain.It has been shown that the 2-layer alpha/β-sandwich domain is for RNA binding. The 3-layer alpha/beta domain is to stabilise the L1-rRNA complex []. The 3-layer domain of ribosomal protein TthL1 hinders binding of intactprotein with RNA due to interdomain flexibility. As a result, the rate of complex formation with mRNA increases for the isolated domain I as compared with
that for intact TthL1 [].
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 a number of eukaryotic and archaebacterial ribosomal proteins; mammalian S19, Drosophila S19, Ascaris lumbricoides S19g (ALEP-1) and S19s, yeast YS16 (RP55A and RP55B), Aspergillus S16 and Haloarcula marismortui HS12.
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 [
,
].L27 is a protein from the large (50S) subunit; it is essential for ribosome function, but its exact role is unclear. It belongs to a family of ribosomal proteins, examples of which are found in bacteria, chloroplasts of plants and red algae and the mitochondria of fungi (e.g. MRP7 from yeast mitochondria). The schematic relationship between these groups of proteins is shown below.Bacterial L27 Nxxxxxxxxx
Algal L27 NxxxxxxxxxPlant L27 tttttNxxxxxxxxxxxxx
Yeast MRP7 tttNxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx't': transit peptide.
'N': N-terminal of mature protein.
Cytoplasmic tRNA 2-thiolation protein 2 (also known as Ncs2/Tuc2 in budding yeasts) is responsible for 2-thiolation of mcm5S2U at tRNA wobble positions of tRNA(Lys), tRNA(Glu) and tRNA(Gln) [
,
]. Its fission yeast homologue, Ctu2 forms a complex with Ctu1 (Ncs6/Tuc1 homologue) and serves as a putative enzyme for the formation of 2-thiouridine [].
The SMC (structural maintenance of chromosomes) family of proteins, exist in virtually all organisms, including bacteria and archaea. The SMC proteins are essential for successful chromosome transmission during replication and segregation of the genome in all organisms. They function together with other proteins in a range of chromosomal transactions, including chromosome condensation, sister-chromatid cohesion, recombination, DNA repair and epigenetic silencing of gene expression [
,
].SMCs are generally present as single proteins in bacteria, and as at least six distinct proteins in eukaryotes. The proteins range in size from approximately 110 to 170kDa, and share a five-domain structure, with globular N- and C-terminal domains separated by a long
(circa 100 nm or 900 residues) coiled coil segment in the centre of which is a globular ''hinge'' domain, characterised by a set of four highly conserved glycine residuesthat are typical of flexible regions in a protein. The amino-terminal domain contains a 'Walker A' nucleotide-binding domain (GxxGxGKS/T), which has been shown by mutational studies to be essential in several proteins. The carboxy-terminal domain contains a sequence (the DA-box) that resembles a 'Walker B' motif (XXXXD, where X is any hydrophobic residue), and a LSGG motif with homology to the signature sequence of the ATP-binding cassette (ABC) family of ATPases [
]. All SMC proteins appear to form dimers, either forming homodimers, as in the case of prokaryotic SMC proteins, or heterodimers between different but related SMC proteins. The dimers form core components of large multiprotein complexes. The best known complexes are cohesin, which is responsible for sister-chromatid cohesion, and condensin, which is required for full chromosome condensation in mitosis. SMC dimers are arranged in an antiparallel alignment. This orientation brings the N- and C-terminal globular domains (from either different or identical protamers) together, which unites an ATP binding site (Walker A motif) within the N-terminal domain with a Walker B motif (DA box) within the C-terminal domain, to form a potentially functional ATPase. Protein interaction and microscopy data suggest that SMC dimers form a ring-like structure which might embrace DNA molecules. Non-SMC subunits associate with the SMC amino- and carboxy-terminal domains.Proteins in this entry include SMC1/2/3/4 from Saccharomyces cerevisiae. SMC1-SMC3 heterodimer is part of the cohesin complex, which is required for sister chromatid cohesion in mitosis and meiosis []. SMC2-SMC4 heterodimer is part of the condensin complex, which is required for chromosome condensation during both mitosis and meiosis [,
].
Nucleoside triphosphate pyrophosphatase Maf-like protein
Type:
Family
Description:
The Maf protein of Bacillus subtilis shares substantial amino acid sequence identity with Escherichia coli YhdE (previously known as OrfE) [
]. Maf-like proteins are conserved in bacteria, archaea, and eukaryotes. Maf proteins have been implicated in cell division arrest []. It has also been proposed that they belong to a family of house-cleaning nucleotide hydrolyzing enzymes which prevent the incorporation of noncanonical nucleotides into cellular DNA []. Maf proteins exhibit nucleotide pyrophosphatase activity against canonical and modified nucleotides, which might represent a molecular mechanism for this dual role in cell division arrest and in house-cleaning []. This entry includes pyrophosphatases, such as YhdE and YceF from E. coli. YhdE is a nucleoside triphosphate pyrophosphatase that hydrolyzes dTTP and UTP [
,
,
]. YceF is a nucleoside triphosphate pyrophosphatase that hydrolyzes 7-methyl-GTP (m7GTP) [].
This entry includes COV1 from Arabidopsis and uncharacterised proteins from bacteria and archaea. COV1 is an integral membrane protein involved in the regulation of vascular patterning in the stem, probably by negatively regulating the differentiation of vascular tissue [
].
This domain can be found in the plant NPR proteins. Arabidopsis NPR1 is a key regulator of the salicylic acid (SA)-mediated systemic acquired resistance (SAR) pathway [
]. Its paralogs, NPR3, and NPR4, bind SA and control the proteasome-mediated degradation of NPR1 through their interaction with NPR1 [].
Human YVH1, also known as dual specificity phosphatase 12 (DUSP12), is a cell survival phosphatase that prevents both thermal and oxidative stress-induced cell death. Furthermore, it associates with multiple ribonucleoprotein particles and may affect a variety of fundamental cellular processes [
]. The enzyme is known as dual specificity protein phosphatase MPK-4 in Drosophila[
]. Yeast YVH1, on the other hand, is required for a late maturation step in the 60S biogenesis pathway [].
Members of this eukaryotic family are part of the group II chaperonin complex called CCT (chaperonin containing TCP-1 or Tailless Complex Polypeptide 1) or TRiC [
,
]. Chaperonins are involved in productive folding of proteins []. They share a common general morphology, a double toroid of 2 stacked rings. The archaeal equivalent group II chaperonin is often called the thermosome []. Both the thermosome and the TCP-1 family of proteins are weakly, but significantly [], related to the cpn60/groEL chaperonin family (see ).
The TCP-1 protein was first identified in mice where it is especially abundant in testis but present in all cell types. It has since been found and characterised in many other animal species, as well as in yeast, plants and protists. The TCP1 complex has a double-ring structure with central cavities where protein folding takes place [
]. TCP-1 is a highly conserved protein of about 60kDa (556 to 560 residues) which participates in a hetero-oligomeric 900kDa double-torus shaped particle [] with 6 to 8 other different, but homologous, subunits []. These subunits, the chaperonin containing TCP-1 (CCT) subunit beta, gamma, delta, epsilon, zeta and eta are evolutionary related to TCP-1 itself [,
]. Non-native proteins are sequestered inside the central cavity and folding is promoted by using energy derived from ATP hydrolysis [,
,
]. The CCT is known to act as a molecular chaperone for tubulin, actin and probably some other proteins [,
].This family consists exclusively of the CCT theta chain (part of a paralogous family) from animals, plants, fungi, and other eukaryotes.
Rfa2 (also known as RPA32) is a component of the replication protein A (RPA) complex, which binds to and removes secondary structure from ssDNA. The RPA complex is involved in DNA replication, repair, and recombination [
].
This family consists of sequences found in a number of hypothetical plant proteins of unknown function. The region of interest contains nine highly conserved cysteine residues and is approximately 160 amino acids in length, which probably represent a zinc-binding domain.
This group represents an U6 snRNA-associated Sm-like protein LSm2. It is a component of LSm protein complexes, which are involved in RNA processing and may function in a chaperone-like manner. LSm2 binds specifically to the 3'-terminal U-tract of U6 snRNA [
].
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 pattern identifies ribosomal protein L6, which is one of the proteins from the large ribosomal subunit.
In Escherichia coli, L6 is known to bind directly to the 23S rRNA and islocated at the aminoacyl-tRNA binding site of the peptidyltransferase centre.
It belongs to a family of ribosomal proteins, which on the basis of sequencesimilarities groups: bacterial, algal chloroplast, cyanelle, archaeal, Marchantia polymorpha mitochondrial L6, yeast mitochondrial YmL6 (gene MRPL6), mammalian, Drosophila melanogaster, plant and yeast L9 [
,
,
]. This signature finds the archaeal L6 proteins, and L9 proteins, L6 proteins from other organisms are found in .
Kin17 is a highly conserved protein that participates in DNA replication, DNA repair and cell cycle progression [
,
,
].Region 51-160 of human Kin17 folds into an atypical winged helix (WH) domain. It consists of a three-α-helix bundle packed against a three-stranded β-sheet. Structural comparison with analogous WH domains reveals that Kin17 WH module presents an additional helix. In addition, helix H3 is not positively charged as in classical DNA-binding WH domains [
]. This domain may be involved in protein-protein interactions.
This entry represents the full-length proteins in which, in higher eukaryotes, the nested domain EDSLL lies. Fra10Ac1 is a highly conserved nuclear protein of unknown function that is highly expressed in brain tissue [
].
