The CBP protein was described as a factor binding to protein kinase A (PKA)-phosphorylated forms of CREB. Since phospshorylation of CREB enhances transcription of downstream target promoters, it was hypothesized that CBP functions as a transcription co-activator. A variety of sequence-specific, DNA-binding factors are found in complex with CBP: these include nuclear steroid receptors, c-Jun, Fos, p53, Sap1, Stat1 and Stat2, MyoD, Ets-1, NFkB, HIF1 , GATA 1, cMyb, and Smad proteins. Further, CBP interact with TBP, TFIIB, TFIID, RNA helicase A, and with RNA poymerase II itself, suggesting that they are recruited to RNA polymerase II holoenzyme. In transient transfection assays increased expression levels of CBP leads to inhibition of cellular growth. The viral oncoproteins Tag and E1a require the association with p300 and CBP to induce entry into S-phase and also inhibit the transcription activity of both proteins on several cellular enhancers/promoter elements. Deletions, translocations and point mutations within the CBP genes have been found in human tumors.

References

1.Dyson HJ,et al. J Biol Chem. 2016 Mar 25;291(13):6714-22.