title: hPop4: a new protein subunit of the human RNase MRP and RNase P ribonucleoprotein complexes.
abstract: RNase MRP is a ribonucleoprotein particle involved in the processing of pre-rRNA. The RNase MRP particle is structurally highly related to the RNase P particle, which is involved in pre-tRNA processing. Their RNA components fold into a similar secondary structure and they share several protein subunits. We have identified and characterised human and mouse cDNAs that encode proteins homologous to yPop4p, a protein subunit of both the yeast RNase MRP and RNase P complexes. The human Pop4 cDNA encodes a highly basic protein of 220 amino acids. Transfection experiments with epitope-tagged hPop4 protein indicated that hPop4 is localised in the nucleus and accumulates in the nucleolus. Immunoprecipitation assays using extracts from transfected cells expressing epitope-tagged hPop4 revealed that this protein is associated with both the human RNase MRP and RNase P particles. Polyclonal rabbit antibodies raised against recombinant hPop4 recognised a 30 kDa protein in total HeLa cell extracts and specifically co-immunoprecipitated the RNA components of the RNase MRP and RNase P complexes. Finally we showed that anti-hPop4 immunoprecipitates possess RNase P enzymatic activity. Taken together, these data show that we have identified a protein that represents the human counterpart of the yeast Pop4p protein.
authors.affiliation: Department of Biochemistry, University of Nijmegen, PO Box 9101, NL-6500 HB Nijmegen, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: van Eenennaam
authors.forename: G J
authors.initials: GJ
authors.lastname: Pruijn
authors.forename: W J
authors.initials: WJ
authors.lastname: van Venrooij
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D002466:Cell Nucleolus / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis; D004722:Endoribonucleases / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D016337:RNA, Catalytic / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D043262:Ribonuclease P; D012261:Ribonucleoproteins / Q000737:chemistry / Q000276:immunology; D017386:Sequence Homology, Amino Acid
chemical_list: D000906:Antibodies; D018076:DNA, Complementary; D016337:RNA, Catalytic; D012261:Ribonucleoproteins; D004722:Endoribonucleases; C058330:mitochondrial RNA-processing endoribonuclease; C468368:RPP14 protein, human; D043262:Ribonuclease P