THE GENE (POLR2L) ENCODING THE HRPB7.6 SUBUNIT OF HUMAN RNA-POLYMERASE

The gene (POLR2L) encoding a 7.6-kDa subunit (hRPB7.6) of human RNA po lymerase has been cloned. It comprises two exons, 116 and 227 bp, resp ectively, interspaced with an intron of about 2.1 kb. This gene, whose localization has been assigned to the short arm of chromosome 11 (pos ition 11p15), is transcribed in HeLa cells as one major messenger RNA, which encodes a 67-residue polypeptide (7645 La) that shares strong h omologies with the corresponding subunits of other eukaryotic and arch aeal RNA polymerase subunits. Like its yeast counterpart (ABC10 beta, encoded by the RPB10 gene), the hRPB7.6 subunit may be shared by all t hree classes of human nuclear RNA polymerase. Cysteine residues charac teristic of an atypical zinc-binding domain are conserved in the homol ogous sequences of all six species analyzed. A small, related RNA poly merase subunit from vaccinia virus exhibits an identical set of cystei nes, suggesting that these residues may contribute to a crucial functi on in the multimeric RNA polymerases. (C) 1996 Academic Press, Inc.