N-terminal acetylation is one of the most common protein modifications in eukaryotes, occurring on approximately 57% and 84% on yeast and human proteins respectively. There are several N-terminal acetylating enzyme complexes (NatA - NatE). Unlike the other complexes, NatD is composed of a single protein, NAT11, and has recently been described to acetylate the Serine N-termini of histones H2A and H4 in yeast. The role these modifications play is unknown; yeast that do not express NAT11 grow at normal rates and have no observable phenotypes. The role of the human homolog is likewise unknown.