POLR1B, Official Symbol POLR1Bprovided by HGNC Official Full Name RNA polymerase I subunit Bprovided by HGNC Primary source HGNC:HGNC:20454 See related Ensembl:ENSG00000125630 MIM:602000; AllianceGenome:HGNC:20454 Gene type protein coding RefSeq status VALIDATED Organism Homo sapiens Lineage Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo Also known as A135; RPA2; TCS4; RPA135; Rpo1-2 Summary Eukaryotic RNA polymerase I (pol I) is responsible for the transcription of ribosomal RNA (rRNA) genes and production of rRNA, the primary component of ribosomes. Pol I is a multisubunit enzyme composed of 6 to 14 polypeptides, depending on the species. Most of the mass of the pol I complex derives from the 2 largest subunits, Rpa1 and Rpa2 in yeast. POLR1B is homologous to Rpa2 (Seither and Grummt, 1996 [PubMed 8921381]).[supplied by OMIM, Mar 2008] Expression Ubiquitous expression in testis (RPKM 8.1), thyroid (RPKM 7.8) and 25 other tissues See more Orthologs mouse all