N-acetyltransferase that acetylates histone H3 at 'Lys-14' and histone H4 at 'Lys-5' and 'Lys-12'. Also acetylates polyamines like putrescine, spermidine and spermine, and certain other small basic proteins like nuclear HMG proteins. acetyl-CoA + L-lysyl-[protein] = CoA + H(+) + N(6)-acetyl-L-lysyl-[protein] Forms homodimers in the absence, and homotetramers in the presence of acetyl-CoA. Autoacetylates in an intermolecular reaction. Belongs to the acetyltransferase family. GNAT subfamily.