hPop1: an autoantigenic protein subunit shared by the human RNase P and RNase MRP ribonucleoproteins.
The eukaryotic endonucleases RNase P and RNase MRP require both RNA and protein subunits for function. Even though the human RNase P and MRP RNAs were previously characterized, the protein composition of the particles remains unknown. We have identified a human a Caenorhabditis elegans sequence showing homology to yPop1, a protein subunit of the yeast RNase P and MRP particles. A cDNA containing the complete coding sequence for the human protein, hPop1, was cloned. Sequence analysis identifies three novel sequence motifs, conserved between the human, C. elegans and yeast proteins. Affinity-purified anti-hPop1 antibodies recognize a single 115 kDa protein in HeLa cell nuclear extracts. Immunoprecipitations with different anti-hPop1 antibodies demonstrate an association of hPop1 with the vast majority of the RNase P and MRP RNAs in HeLa cell nuclear extracts. Additionally, anti-hPop1 immunoprecipitates possess RNase P enzymatic activity. These results establish hPop1 as the first identified RNase P and MRP protein subunit from humans. Anti-hPop1 antibodies generate a strong nucleolar and a weaker homogeneous nuclear staining in HeLa cells. A certain class of autoimmune patient serum precipitates in vitro-translated hPop1. hPop1 is therefore an autoantigen in patients suffering from connective tissue diseases.
Lygerou
Z
Z
EMBL, Heidelberg, Germany.
Pluk
H
H
van Venrooij
W J
WJ
Séraphin
B
B
D000595:Amino Acid Sequence; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001323:Autoantibodies / Q000097:blood; D001324:Autoantigens / Q000737:chemistry / Q000235:genetics*; D017173:Caenorhabditis elegans / Q000235:genetics; D002352:Carrier Proteins; D003001:Cloning, Molecular; D003240:Connective Tissue Diseases / Q000276:immunology; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000235:genetics; D004722:Endoribonucleases / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D011487:Protein Conformation; D016337:RNA, Catalytic / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D043262:Ribonuclease P; D012261:Ribonucleoproteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
D051017:Apoptosis Regulatory Proteins; D001323:Autoantibodies; D001324:Autoantigens; D002352:Carrier Proteins; D018076:DNA, Complementary; C089992:POP1 protein, S cerevisiae; C490350:POP1 protein, human; D016337:RNA, Catalytic; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; D004722:Endoribonucleases; C058330:mitochondrial RNA-processing endoribonuclease; C468368:RPP14 protein, human; D043262:Ribonuclease P