The p300-CBP coactivator family in humans is composed of two closely related transcriptional co-activating proteins (or coactivators):

1. p300 (also called EP300 or E1A binding protein p300)
2. CBP (also known as CREB-binding protein or CREBBP)

Both p300 and CBP interact with numerous transcription factors and act to increase the expression of their target genes.

• Kasper LH, Fukuyama T, Biesen MA, Boussouar F, Tong C, de Pauw A, Murray PJ, van Deursen JM, Brindle PK (Feb 2006). “Conditional knockout mice reveal distinct functions for the global transcriptional coactivators CBP and p300 in T-cell development”. Molecular and Cellular Biology. 26 (3): 789–809. doi:10.1128/MCB.26.3.789-809.2006. PMC 1347027. PMID 16428436.
• Vo N, Goodman RH (Apr 2001). “CREB-binding protein and p300 in transcriptional regulation”. The Journal of Biological Chemistry. 276 (17): 13505–8. doi:10.1074/jbc.R000025200. PMID 11279224. S2CID 41294840.

Protein structure

p300 and CBP have similar structures. Both contain five protein interaction domains: the nuclear receptor interaction domain (RID), the KIX domain (CREB and MYB interaction domain), the cysteine/histidine regions (TAZ1/CH1 and TAZ2/CH3) and the interferon response binding domain (IBiD). The last four domains, KIX, TAZ1, TAZ2 and IBiD of p300, each bind tightly to a sequence spanning both transactivation domains 9aaTADs of transcription factor p53. In addition p300 and CBP each contain a protein or histone acetyltransferase (PAT/HAT) domain and a bromodomain that binds acetylated lysines and a PHD finger motif with unknown function. The conserved domains are connected by long stretches of unstructured linkers.

• The prediction for 9aaTADs (for both acidic and hydrophilic transactivation domains) is available online from ExPASy http://us.expasy.org/tools/ Archived 2010-07-16 at the Wayback Machine and EMBnet Spain “EMBnet Austria: Detect 9aaTAD Pattern”. Archived from the original on 2013-07-04. Retrieved 2013-07-04.
• Spiegelman BM, Heinrich R (Oct 2004). “Biological control through regulated transcriptional coactivators”. Cell. 119 (2): 157–67. doi:10.1016/j.cell.2004.09.037. PMID 15479634. S2CID 14668705.