Protein Domain : Ribonuclease P subunit, Rpr2/Snm1/Rpp21 IPR007175

Type	Family
Description	This entry contains ribonuclease P (Rnp) proteins from eukaryotes and archaea. Rnp is a ubiquitous ribozyme that catalyzes a Mg2 -dependent hydrolysis to remove the 5'-leader sequence of precursor tRNA (pre-tRNA) [ , ]. Archaeal and eukaryotic RNase P consist of a single RNA and archaeal RNase P has four or five proteins, while eukaryotic RNase P consists of 9 or 10 proteins. Eukaryotic and archaeal RNase P RNAs cooperatively function with protein subunits in catalysis []. Human RNase P is composed of a singular protein Pop1 and three subcomplexes, the Rpp20-Rpp25 heterodimer, Pop5-Rpp14-(Rpp30)2-Rpp40 heteropentamer, and Rpp21-Rpp29-Rpp38 heterotrimer. Although both Pop5 and Rpp14 have similar protein structure, they share a very limited sequence similarity. Moreover, the C-terminal fragments after the conserved beta sheets in Pop5 and Rpp14 exhibit distinct structural features that mediate interactions with Pop1 and Rpp40, respectively [ ].In the hyperthermophilic archaeon Pyrococcus horikoshii OT3, RNase P is composed of the RNase P RNA (pRNA) and five proteins (PhoPop5, PhoRpp38, PhoRpp21, PhoRpp29, and PhoRpp30) [ , ].This entry includes Rpp21 from animals, Snm1/Rpr2 from yeasts and RNP4 from archaea [ , ]. Snm1 is a subunit of RNase MRP (mitochondrial RNA processing), a ribonucleoprotein endoribonuclease that has roles in both mitochondrial DNA replication and nuclear 5.8S rRNA processing. Snm1 is an RNA binding protein that binds the MRP RNA specifically []. This subunit possibly binds the precursor tRNA [].
Short Name	Rpr2/Snm1/Rpp21