Ribonuclease P (RNase P) and Ribonuclease MRP (RNase MRP) are small nuclear ribonucleoproteins (snRNPs) that act on RNA substrates in vitro. RNase P and RNase MRP, which accumulate in the nucleolus, have a similar RNA component and also have several protein subunits in common. RNase P, which consists of a complex of an RNA species, POP1, POP5 and at least seven Rpps, remove the 5’ leader sequences from precursor tRNA molecules. Rpp20 (ribonuclease P protein subunit p20), also known as POP7 (processing of precursor 7, ribonuclease P/MRP subunit) or RPP2, is a 140 amino acid nuclear protein that belongs to the histone-like Alba family and functions as a component of nuclear RNase P and RNase MRP ribonucleoproteins. The gene encoding Rpp20 maps to human chromosome 7q22.1 and mouse chromosome 5 G2.
