RNA Polymerase I, DNA Directed Polypeptide B (POLR1B)

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.Rpa2, the second largest pol I subunit. The 3,978-bp open reading frame encodes a 1,136-amino acid polypeptide with a calculated molecular mass of 128 kD. Sequence alignment with the corresponding Drosophila and yeast genes revealed the same level of sequence similarity among Rpa2 genes as exists for Rpa1 genes across diverse species