A FAMILY OF TRANSCRIPTIONAL ADAPTER PROTEINS TARGETED BY THE E1A ONCOPROTEIN

THE cellular protein p300 is a target of the adenoviral E1A oncoprotei n and is thought to participate in preventing the G0/G1 transition in the cell cycle, activating certain enhancers and stimulating different iation pathways(1). CBP is a protein that is associated with and coact ivates the transcription factor CREB, mediating the induction by cycli c AMP of certain responsive promoters(2-4). The sequences of p300 and CBP are highly related(4,5). We show here that p300, like CBP2, can st imulate transcription, This activity is directly aml specifically inhi bited by E1A. We also find that CBP exists in a DNA-bound complex cont aining a member of the CREB family and that E1A and CBP interact with one another in vivo. In keeping with the idea that E1A functionally ta rgets CBP, cAMP-dependent transcription is repressed by E1A. Thus, p30 0 and CBP define a family of transcriptional adaptor proteins that are specifically targeted by the E1A oncoprotein.