p300/CBP-associated factor (PCAF), also known as lysine acetyl-transferase 2B (KAT2B), is a transcriptional adaptor protein and histone acetyl-transferase (HAT) that functions as the catalytic subunit of the PCAF transcriptional co-activator complex (1). PCAF is 73% homologous to GCN5L2, another HAT protein found in similar complexes (1,2). Like GCN5L2, PCAF acetylates histone H3 on Lys14 and histone H4 on Lys8, both of which contribute to gene activation by modulating chromatin structure and recruiting additional co-activator proteins that contain acetyl-lysine binding bromo-domains (3). PCAF also acetylates non-histone proteins including transcriptional activators (p53, E2F1, MyoD), general transcription factors (TFIIEβ and TFIIF) and architectural DNA binding proteins (HMGA1 and HMG17) (4-10). Acetylation of these proteins regulates their nuclear localization, protein stability, DNA binding, and co-activator association. |