A family of transcriptional adaptor proteins targeted by the E1A oncoprotein

Abstract

THE cellular protein p300 is a target of the adenoviral El A oncoprotein and is thought to participate in preventing the GO/G1 transition in the cell cycle, activating certain enhancers and stimulating differentiation pathways¹. CBP is a protein that is associated with and coactivates the transcription factor CREB, mediating the induction by cyclic 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 stimulate transcription. This activity is directly and specifically inhibited by E1A. We also find that CBP exists in a DNA-bound complex containing a member of the CREB family and that El A and CBP interact with one another in vivo. In keeping with the idea that El A functionally targets CBP, cAMP-dependent transcription is repressed by El A. Thus, p300 and CBP define a family of transcriptional adaptor proteins that are specifically targeted by the El A oncoprotein.