Rpp14 and Rpp29, two protein subunits of human ribonuclease P

In HeLa cells, the tRNA processing enzyme ribonuclease P (RNase P) consists of an RNA molecule associated with at least eight protein subunits, hPop1, Rpp14, Rpp20, Rpp25, Rpp29, Rpp30, Rpp38, and Rpp40. Five of these protein s (hPap1p, Rpp20, Rpp30, Rpp38, and Rpp40) have been partially characterize d. Here we report an the cDNA cloning and immunobiochemical analysis of Rpp 14 and Rpp29. Polyclonal rabbit antibodies raised against recombinant Rpp14 and Rpp29 recognize their corresponding antigens in HeLa cells and precipi tate catalytically active RNase P. Rpp29 shows 23% identity with Pop4p, a s ubunit of yeast nuclear RNase P and the ribosomal RNA processing enzyme RNa se MRP. Rpp14, by contrast, exhibits no significant homology to any known y east gene. Thus, human RNase P differs in the details of its protein compos ition, and perhaps in the functions of some of these proteins, from the yea st enzyme.