Depletions of a transcription extract with the anti-hRPC155 antibody specifically reduce transcription from the VAI promoter. Whole cell extract was incubated with preimmune (lane 2) or anti-hRPC155 (lanes 3–5) beads with either no peptide (lane 2,3) or specific (peptide CHS499, lane 5) or nonspecific (peptide CSH498, lane 4) peptide, as detailed in Methods. Aliquots of nontreated (lane 1) or the variously treated extracts were then tested for transcription from the Ad2 VAI promoter (top) or the Ad2 major late promoter (bottom). The signals corresponding to correct initiation from the VAI or major late (ML) promoters are indicated. Immunoblots indicated that extract treated with the specific antibody contained ∼50% of the hRPC155 present in extract treated with the preimmune antibodies (data not shown).
