N-alpha-acetyltransferase that acetylates the N-terminus of proteins that retain their initiating methionine (By similarity). Has a broad substrate specificity: able to acetylate the initiator methionine of most peptides, except for those with a proline in second position (By similarity). Also displays N-epsilon-acetyltransferase activity by mediating acetylation of the side chain of specific lysines on proteins (By similarity). The relevance of N-epsilon-acetyltransferase activity is however unclear (By similarity). Required for sister chromatid cohesion during mitosis by promoting binding of CDCA5/sororin to cohesin (By similarity). Essential in embryonic cell proliferation and survival (PubMed:16484612). acetyl-CoA + N-terminal L-methionyl-L-alanyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-alanyl-[protein] acetyl-CoA + N-terminal L-methionyl-L-seryl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-seryl-[protein] acetyl-CoA + N-terminal L-methionyl-L-valyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-valyl-[protein] acetyl-CoA + N-terminal L-methionyl-L-threonyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-threonyl-[protein] acetyl-CoA + N-terminal L-methionyl-L-lysyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-lysyl-[protein] acetyl-CoA + N-terminal L-methionyl-L-leucyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-leucyl-[protein] acetyl-CoA + N-terminal L-methionyl-L-phenylalanyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-phenylalanyl-[protein] acetyl-CoA + N-terminal L-methionyl-L-tyrosyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-tyrosyl-[protein] Interacts with naa35. Localizes to the cytoplasm in interphase cells. Until 48 hpf, highly expressed in developing vascular structures and epidermis. By 48 hpf, becomes restricted to the developing head. By 5 dpf, observed only in the epidermis. Belongs to the acetyltransferase family. GNAT subfamily.