PCAF

P300/CBP-associated factor (PCAF), also known as K(lysine) acetyltransferase 2B (KAT2B), is a human is_associated_with::gene and transcriptional coactivator associated with is_associated_with::p53.

Structure
Several domains of PCAF can act independently or in unison to enable its functions. PCAF has separate is_associated_with::acetyltransferase and is_associated_with::E3 ubiquitin ligase domains as well as a is_associated_with::bromodomain for interaction with other proteins. PCAF also possesses sites for its own acetylation and ubiquitination.

Function
CBP and p300 are large nuclear proteins that bind to many sequence-specific factors involved in cell growth and/or differentiation, including is_associated_with::c-jun and the adenoviral oncoprotein E1A. The protein encoded by the PCAF gene associates with p300/CBP. It has in vitro and in vivo binding activity with CBP and p300, and competes with E1A for binding sites in p300/CBP. It has is_associated_with::histone acetyl transferase activity with core is_associated_with::histones and is_associated_with::nucleosome core particles, indicating that this protein plays a direct role in transcriptional regulation.

Regulation
The is_associated_with::acetyltransferase activity and cellular location of PCAF are regulated through acetylation of PCAF itself. PCAF may be autoacetylated (acetylated by itself) or by p300. Acetylation leads to migration to the nucleus and enhances its acetyltransferase activity. PCAF interacts with and is deacetylated by is_associated_with::HDAC3, leading to a reduction in PCAF acetyltransferase activity and cytoplasmic localisation.

Protein interactions
PCAF forms complexes with numerous proteins that guide its activity. For example PCAF is recruited by ATF to acetylate is_associated_with::histones and promote transcription of ATF4 target genes.

Targets
There are various protein targets of PCAF's acetyltransferase activity including transcription factors such as Fli1, p53 and numerous histone residues. is_associated_with::Hdm2, itself a ubiquitin ligase that targets p53, has also been demonstrated to be a target of the ubiquitin-ligase activity of PCAF.

Interactions
PCAF has been shown to interact with:


 * is_associated_with::BRCA2,
 * CTNNB1,
 * CREBBP,
 * is_associated_with::EVI1,
 * is_associated_with::HNF1A,
 * is_associated_with::IRF1,
 * is_associated_with::IRF2,
 * is_associated_with::KLF13,
 * is_associated_with::Mdm2
 * is_associated_with::Myc,
 * NCOA1,
 * is_associated_with::POLR2A,
 * is_associated_with::RBPJ,
 * is_associated_with::TCF3,
 * TRRAP, and
 * TWIST1.