The protein encoded by the NCOA1 gene acts as a transcriptional coactivator for steroid and nuclear hormone receptors. It is a member of the p160/steroid receptor coactivator (SRC) family and like other family members has histone acetyltransferase activity and contains a nuclear localization signal, as well as bHLH and PAS domains. The product of this gene binds nuclear receptors directly and stimulates the transcriptional activities in a hormone-dependent fashion. Alternatively spliced transcript variants encoding different isoforms have been identified.Synonyms: BHLHE74, Class E basic helix-loop-helix protein 74, NCoA-1, NY-REN-52, Nuclear receptor coactivator 1, Protein Hin-2, RIP160, SRC-1, Steroid receptor coactivator 1