InterPro domain: IPR007175

This entry includes Rpp21 from animals, Snm1/Rpr2 from yeasts and RNP4 from archaea [ 1 , 2 ]. 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 [ 3 ]. This subunit possibly binds the precursor tRNA [ 4 ].

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) [ 4 ]. Archaeal and eukaryote 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 [ 5 ].

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 [ 6 ].

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) [ 6 , 7 ].

1. Interactions among the protein and RNA subunits of Saccharomyces cerevisiae nuclear RNase P. Proc. Natl. Acad. Sci. U.S.A. 99, 2684-9
2. Function and subnuclear distribution of Rpp21, a protein subunit of the human ribonucleoprotein ribonuclease P. RNA 7, 1153-64
3. Mutagenesis of SNM1, which encodes a protein component of the yeast RNase MRP, reveals a role for this ribonucleoprotein endoribonuclease in plasmid segregation. Mol. Cell. Biol. 19, 7857-69
4. The nucleotide sequence of chromosome I from Saccharomyces cerevisiae. Proc. Natl. Acad. Sci. U.S.A. 92, 3809-13
5. Rpp14 and Rpp29, two protein subunits of human ribonuclease P. RNA 5, 153-7
6. Characterization of the archaeal ribonuclease P proteins from Pyrococcus horikoshii OT3. J Biochem 140, 293-8
7. Structural basis for activation of an archaeal ribonuclease P RNA by protein cofactors. Biosci Biotechnol Biochem 81, 1670-1680