THE CELLULAR C1 FACTOR OF THE HERPES-SIMPLEX VIRUS ENHANCER COMPLEX IS A FAMILY OF POLYPEPTIDES

The alpha/immediate early genes of herpes simplex virus are regulated by the specific assembly of a multiprotein enhancer complex containing the Oct-1 POU domain protein, the viral alpha-transinduction factor a lpha TIF, (VP16, ICP25), and the C1 cellular factor, The C1 factor fro m mammalian cells is a heterogeneous but related set of polypeptides t hat interact directly with the alpha-transinduction factor to form a h eteromeric protein complex, The isolation of cDNAs encoding the polype ptides of the C1 factor suggests that these proteins are proteolytic p roducts of a novel precursor. The sequence of the amino termini of the se polypeptide products indicate that the proteins are generated by si te-specific cleavages within a reiterated 20-amino acid sequence. Alth ough the C1 factor appears to be ubiquitously expressed, it is localiz ed to subnuclear structures in specific cell types.