PCAF Protein, Human (His)

KAT2B functions as a histone acetyltransferase (HAT) that promotes transcriptional activation. It exhibits significant histone acetyltransferase activity with core histones (H3 and H4) and nucleosome core particles, with a strong preference for acetylation of H3 at 'Lys-9' (H3K9ac). KAT2B also acetylates non-histone proteins, including ACLY, MAPRE1/EB1, PLK4, RRP9/U3-55K, and TBX5. It inhibits cell-cycle progression and counteracts the mitogenic activity of the adenoviral oncoprotein E1A. Additionally, KAT2B acts as a circadian transcriptional coactivator, enhancing the activity of NPAS2-BMAL1 and CLOCK-BMAL1 heterodimers. In heart and limb development, it mediates TBX5 acetylation, regulating its nucleocytoplasmic shuttling. KAT2B negatively regulates centrosome amplification by acetylating PLK4 and impairs pre-rRNA processing by acetylating RRP9/U3-55K, a core subunit of the U3 snoRNP complex. It also promotes dynamic kinetochore-microtubule interactions in early mitosis by acetylating MAPRE1/EB1 and acetylates spermidine. During HIV-1 infection, KAT2B is recruited by the viral protein Tat, regulating Tat's transactivating activity and potentially aiding in chromatin remodeling of proviral genes.