Nuclear receptor coactivator that directly binds nuclear receptors and stimulates the transcriptional activities in a hormone-dependent fashion. Involved in the coactivation of different nuclear receptors, such as for steroids (PGR, GR and ER), retinoids (RXRs), thyroid hormone (TRs) and prostanoids (PPARs). Also involved in coactivation mediated by STAT3, STAT5A, STAT5B and STAT6 transcription factors. Displays histone acetyltransferase activity toward H3 and H4; the relevance of such activity remains however unclear. Plays a central role in creating multisubunit coactivator complexes that act via remodeling of chromatin, and possibly acts by participating in both chromatin remodeling and recruitment of general transcription factors. Required with NCOA2 to control energy balance between white and brown adipose tissues. Required for mediating steroid hormone response (By similarity). acetyl-CoA + L-lysyl-[protein] = CoA + H(+) + N(6)-acetyl-L-lysyl-[protein] Interacts with NCOA6 and NCOA2. Interacts with the FDL motif of STAT5A and STAT5B. Interacts with the LXXLL motif of STAT6. Interacts with STAT3 following IL-6 stimulation. Interacts with the basal transcription factor GTF2B. Interacts with COPS5, NR3C1, PCAF and TTLL5/STAMP. Interacts with the histone acetyltransferases EP300 and CREBBP, and the methyltransferase CARM1. Interacts with UBE2L3; they functionally interact to regulate progesterone receptor transcriptional activity. Interacts with PRMT2 and DDX5. Interacts with ASXL1. Interacts with PRMT6. Interacts (via LXXLL 1, 2 and 3 motifs) with RORC (via AF-2 motif). Interacts in a ligand-dependent fashion with RXRA. Interacts with TRIP4. Interacts with NR4A3. Interacts with VDR. The C-terminal (1107-1447) part mediates the histone acetyltransferase (HAT) activity. Contains 7 Leu-Xaa-Xaa-Leu-Leu (LXXLL) motifs. LXXLL motifs 3, 4 and 5 are essential for the association with nuclear receptors. Sumoylated; sumoylation increases its interaction with PGR and prolongs its retention in the nucleus. It does not prevent its ubiquitination and does not exert a clear effect on the stability of the protein (By similarity). Ubiquitinated; leading to proteasome-mediated degradation. Ubiquitination and sumoylation take place at different sites (By similarity). Belongs to the SRC/p160 nuclear receptor coactivator family.