E1A binding protein p300 (p300) and CBP (CREB binding protein) are highly related transcriptional coactivators. Both proteins have been identified through protein interaction assays. In addition to interacting with a variety of cellular factors and oncoproteins, loss of the wild type CBP alleles in isolated tumors suggests th at CBP/p300 might serve as tumor suppressors. The ability of p300 to acetylate many transcription factors, including tumor suppressor p53, E2 factor (E2F), transcription factors II E and -F (TFIIE and -F) etc. demonstrates a novel mechanism of targeted p300 regulation of gene expression. Mutations in the gene encoding the protein have been linked to Rubinstein-Taybi syndrome (RSTS).
