Histone acetyltransferase that catalyzes histone H4 acetylation at Lys-5- and Lys-8 (H4K5ac and H4K8ac) or Lys-16 (H4K16ac), depending on the context.Catalytic component of the MSL histone acetyltransferase complex, a multiprotein complex that mediates the majority of histone H4 acetylation at Lys-16 (H4K16ac), an epigenetic mark that prevents chromatin compaction.