Catalytic component of the NatC N-terminal acetyltransferase. 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-isoleucyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-isoleucyl-[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-tryptophyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-tryptophyl-[protein] acetyl-CoA + N-terminal L-methionyl-L-tyrosyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-tyrosyl-[protein] Belongs to the acetyltransferase family. MAK3 subfamily.