As part of the NSL complex, KAT8 binds to a subset of active gene promoters, where it stimulates TAF1 binding, through H4K5 and H4K8 acetylation. This facilitates Pol II recruitment and transcription initiation. As part of the MSL complex, KAT8 catalyzes the bulk of H4K16ac in open chromatin regions and, especially, in gene bodies. K1, KANSL1; K2, KANSL2; K3, KANSL3; K8, KAT8; M1, MSL1; M2, MSL2; M3, MSL3.