N-alpha-acetyltransferase 50 (Naa50)

N-alpha-acetyltransferase that acetylates the N-terminus of proteins which retain their initiating methionine. Has a wide substrate specificity: able to acetylate the initiator methionine of the majority of peptides, except for people who have a proline in 2nd position.

Also displays N-epsilon-acetyltransferase activity by mediating acetylation of the side chain of specific lysines on proteins. The relevance of N-epsilon- acetyltransferase activity is however unclear: able to acetylate H4 in vitro, but this result hasn't been confirmed in vivo.