N-alpha-acetyltransferase that specifically mediates the acetylation of the N-terminal residues of histones H4 and H2A (PubMed:21935442, PubMed:25619998). In contrast to other N-alpha-acetyltransferase, has a very specific selectivity for histones H4 and H2A N-terminus and specifically recognizes the 'Ser-Gly-Arg-Gly sequence' (PubMed:21935442, PubMed:25619998). Acts as a negative regulator of apoptosis (PubMed:26666750). May play a role in hepatic lipid metabolism (By similarity). acetyl-CoA + N-terminal L-seryl-[histone H4] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-seryl-[histone H4] acetyl-CoA + N-terminal L-seryl-[histone H2A] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-seryl-[histone H2A] Widely expressed; with the highest expression level in liver and the lowest expression in brain (at protein level). Down-regulated in hepatocellular carcinoma tissues. Belongs to the acetyltransferase family. NAA40 subfamily. Probable cloning artifact.