Component of the NuA4 histone acetyltransferase complex which is involved in transcriptional activation of select genes principally by acetylation of nucleosomal histones H4 and H2A. This modification may both alter nucleosome - DNA interactions and promote interaction of the modified histones with other proteins which positively regulate transcription. May be required for transcriptional activation of E2F1 and MYC target genes during cellular proliferation. The NuA4 complex ATPase and helicase activities seem to be, at least in part, contributed by the association of RUVBL1 and RUVBL2 with EP400. Component of a SWR1-like complex that specifically mediates the removal of histone H2A.Z/H2AZ1 from the nucleosome (By similarity). Regulates transcriptional activity of ZNF42. Component of the NuA4 histone acetyltransferase complex which contains the catalytic subunit KAT5/TIP60 and the subunits EP400, TRRAP/PAF400, BRD8/SMAP, EPC1, DMAP1/DNMAP1, RUVBL1/TIP49, RUVBL2, ING3, actin, ACTL6A/BAF53A, MORF4L1/MRG15, MORF4L2/MRGX, MRGBP, YEATS4/GAS41, VPS72/YL1 and MEAF6. May also participate in the formation of NuA4 related complexes which lack the KAT5/TIP60 catalytic subunit, but which include the SWI/SNF related protein SRCAP. The NuA4 complex interacts with MYC. EP400 interacts with TRRAP, RUVBL1 and RUVBL2. Component of a SWR1-like complex (By similarity). Interacts with ZNF42. Interacts with PHF5A. Expressed in brain, thymus, lung, liver, spleen, kidney, colon and bone marrow. Belongs to the SNF2/RAD54 helicase family. SWR1 subfamily. Intron retention. Intron retention. Truncated N-terminus.