The nuclear RNase P of Saccharomyces cerevisiae is made up of at least nine protein subunits; Pop1, Pop3, Pop4, Pop5, Pop6, Pop7, Pop8, Rpr2 and Rpp1. Many of these subunits seem to be present also in the RNase MRP, with the exception of Rpr2 (Rpp21) which is unique to RNase P. Human nuclear RNase P and MRP appear to contain at least 10 protein subunits, Rpp14, Rpp20, Rpp21, Rpp25, Rpp29, Rpp30, Rpp38, Rpp40, hPop1 and hPop5, although there is recent evidence that not all of these subunits are shared between P and MRP. Archaeal RNase P has at least four protein subunits homologous to eukaryotic RNase P/MRP proteins [2]. In the yeast RNase P, Pop6 and Pop7 (the Rpp20 homologue) interact with each other and they are both interaction partners of Pop4 [4]; in the human MRP Rpp25 and Rpp20 interact with each other [2] and Rpp25 binds to Rpp29 (Pop4) [3].

1: Rpp2, an essential protein subunit of nuclear RNase P, is required for processing of precursor tRNAs and 35S precursor rRNA in Saccharomyces cerevisiae. Stolc V, Katz A, Altman S; Proc Natl Acad Sci U S A. 1998;95:6716-6721. PMID:9618478

2: Mutual interactions between subunits of the human RNase MRP ribonucleoprotein complex. Welting TJ, van Venrooij WJ, Pruijn GJ; Nucleic Acids Res. 2004;32:2138-2146. PMID:15096576

3: Inventory and analysis of the protein subunits of the ribonucleases P and MRP provides further evidence of homology between the yeast and human enzymes. Rosenblad MA, Lopez MD, Piccinelli P, Samuelsson T; Nucleic Acids Res. 2006;34:5145-5156. PMID:16998185

4: Specific binding of a Pop6/Pop7 heterodimer to the P3 stem of the yeast RNase MRP and RNase P RNAs. Perederina A, Esakova O, Koc H, Schmitt ME, Krasilnikov AS; RNA. 2007;13:1648-1655. PMID:17717080