Gene organization and protein sequence of the small subunits of Schizosaccharomyces pombe RNA polymerase II

RNA polymerase II purified from the fission yeast Schizosaccharomyces pombe contains 10 different species of polypeptides. Previously, we cloned and sequenced both cDNA and the genes encoding the four large subunits, Rpb1, Rpb2, Rpb3 and Rpb5. Later, other groups isolated the genes for Rpb6 and Rpb12 and cDNA for Rpb10. Here, we cloned both cDNA and the genes encoding four small subunits, Rpb7, Rpb8, Rpb10 and Rpb11. These genes were found to encode Rpb7, Rpb8, Rpb10 and Rpb11 consisting of 172 (19,103 Da), 125 (14,300 Da), 71 (8276 Da) and 123 (14,127 Da) amino acid residues, respectively. All these four subunits are homologous to the corresponding subunits of Saccharomyces cerevisiae RNA polymerase II. The rpb7 gene contains one intron, whereas the rpb8, rpb10 and rpb11 genes contain two introns. Taken altogether, the gene organization and the predicted protein sequence have been determined for all 10 subunits of the S. pombe RNA polymerase II.