Catalytic subunit of the NuA4 histone acetyltransferase complex which is involved in transcriptional activation of select genes principally by acetylation of nucleosomal histones H4 and H2A (PubMed:12776177, PubMed:15042092, PubMed:15121871, PubMed:15310756, PubMed:14966270, PubMed:16387653, PubMed:19909775, PubMed:15196461). This modification may both alter nucleosome-DNA interactions and promote interaction of the modified histones with other proteins which positively regulate transcription (PubMed:12776177, PubMed:15042092, PubMed:15121871, PubMed:15310756, PubMed:14966270, PubMed:15196461). This complex may be required for the activation of transcriptional programs associated with oncogene and proto-oncogene mediated growth induction, tumor suppressor mediated growth arrest and replicative senescence, apoptosis, and DNA repair (PubMed:15196461). NuA4 may also play a direct role in DNA repair when recruited to sites of DNA damage (PubMed:15196461). Component of a SWR1-like complex that specifically mediates the removal of histone H2A.Z/H2AZ1 from the nucleosome (PubMed:24463511). Also acetylates non-histone proteins, such as ATM, NR1D2, RAN, FOXP3, ULK1 and RUBCNL/Pacer (PubMed:16141325, PubMed:17360565, PubMed:17996965, PubMed:29040603, PubMed:30704899). Directly acetylates and activates ATM (PubMed:16141325). Relieves NR1D2-mediated inhibition of APOC3 expression by acetylating NR1D2 (PubMed:17996965). Promotes FOXP3 acetylation and positively regulates its transcriptional repressor activity (PubMed:17360565). Acetylates RAN at 'Lys-134' (PubMed:29040603). Together with GSK3 (GSK3A or GSK3B), acts as a regulator of autophagy: phosphorylated at Ser-86 by GSK3 under starvation conditions, leading to activate acetyltransferase activity and promote acetylation of key autophagy regulators, such as ULK1 and RUBCNL/Pacer (PubMed:30704899).