STRUCTURE OF THE GENE ENCODING THE 14.5 KDA SUBUNIT OF HUMAN RNA POLYMERASE-II

The structure of the gene encoding the 14.5 kDa subunit of the human R NA polymerase II (or B) has been elucidated. The gene consists of six exons, ranging from 52 to over 101 bp, interspaced with five introns r anging from 84 to 246 bp. It is transcribed into three major RNA speci es, present at low abundance in exponentially growing HeLa cells. The corresponding messenger RNAs contain the same open reading frame encod ing a 125 amino acid residue protein, with a calculated molecular weig ht of 14,523 Da. This protein (named hRPB14.5) shares strong homologie s with the homologous polymerase subunits encoded by the Drosophila (R pII15) and yeast (RPB9) genes. Cysteines characteristic of two zinc fi ngers are conserved in all three corresponding sequences and, like the yeast protein, the hRPB14.5 subunit exhibits zinc-binding activity.