The carboxy-terminal domain shared by the bovine papillomavirus E2 transactivator and repressor proteins contains a specific DNA binding activity.

The E2 open reading frame of bovine papilloma virus 1 (BPV-1) has been shown to encode both positive and negative acting transcriptional regulatory factors. The DNA binding properties of these factors were analysed to investigate the mechanism by which they might regulate viral gene expression. Polypeptides corresponding to the full-length E2 product and a shorter protein thought to represent the repressor function were synthesized in vitro by translation of T7 polymerase generated transcripts. Using rabbit antisera generated against synthetic peptides from the E2 open reading frame, it was possible to immunoprecipitate each of these products and show that each was capable of binding the same specific sequence located at several sites in the BPV-1 genome. This DNA binding property was mapped to a conserved carboxy-terminal domain of 101 amino acids by analysis of truncated polypeptides synthesized from the E2 open reading frame.