Component of the ATAC complex, a complex with histone acetyltransferase activity on histones H3 and H4. Required for the function of some acidic activation domains, which activate transcription from a distant site (By similarity). Binds double- stranded DNA. Binds dinucleosomes, probably at the linker region between neighboring nucleosomes. Plays a role in chromatin remodeling. May promote TP53/p53 'Lys-321' acetylation, leading to reduced TP53 stability and transcriptional activity (PubMed:22644376). May also promote XRCC6 acetylation thus facilitating cell apoptosis in response to DNA damage (PubMed:22644376). {ECO:0000250|UniProtKB:Q8CHV6, ECO:0000269|PubMed:19103755, ECO:0000269|PubMed:22644376}. This is the function of TADA2A (transcriptional adaptor 2A, Ensembl gene identifier ENSG00000276234).