May be a transcriptional coactivator of the nuclear receptor ESR1 required to induce the expression of a subset of estradiol target genes, such as CCND1, MYC and E2F1. May play a role in the recruitment or occupancy of CREBBP at some ESR1 target gene promoters. May be required for histone hyperacetylation (By similarity). ATP + H2O = ADP + H(+) + phosphate Interaction with ESR1 and NCOA3 is enhanced by estradiol. Interacts with acetylated lysine residues on histone H1.4, H2A, H2B and H3 (in vitro) (By similarity). Belongs to the AAA ATPase family.