本酶催化的反应为(1) Acetyl-CoA + An N-Terminal-L-Methionyl-L-Leucyl-[Protein] = An N-Terminal-Nalpha-Acetyl-L-Methionyl-L-Leucyl-[Protein] + CoA;;(2) Acetyl-CoA + An N-Terminal-L-Methionyl-L-Isoleucyl-[Protein] = An N-Terminal-Nalpha-Acetyl-L-Methionyl-L-Isoleucyl-[Protein] + CoA;;(3) Acetyl-CoA + An N-Terminal-L-Methionyl-L-Phenylalanyl-[Protein] = An N-Terminal-Nalpha-Acetyl-L-Methionyl-L-Phenylalanyl-[Protein] + CoA;;(4) Acetyl-CoA + An N-Terminal-L-Methionyl-L-Tryptophyl-[Protein] = An N-Terminal-Nalpha-Acetyl-L-Methionyl-L-Tryptophyl-[Protein] + CoA;;(5) Acetyl-CoA + An N-Terminal-L-Methionyl-L-Tyrosyl-[Protein] = An N-Terminal-Nalpha-Acetyl-L-Methionyl-L-Tyrosyl-[Protein] + CoA,系统名称为Acetyl-CoA:N-Terminal-Met-Leu/Ile/Phe/Trp/Tyr-[Protein] Met Nalpha-Acetyltransferase,N端乙酰转移酶(NAT)催化将来自乙酰-CoA的乙酰基共价连接到蛋白N末端的游离α-氨基上。这种不可逆修饰中和了N末端的正电荷,使N末端残基变大且更具疏水性,还可能在膜定位和基因沉默中发挥作用。NatC复合体存在于所有真核生物中,专一靶向第二位为大体积疏水残基(包括Leu、Ile、Phe、Trp和Tyr残基)的N末端L-甲硫氨酸残基。