Displays alpha (N-terminal) acetyltransferase activity. Proposed alternative catalytic subunit of the N-terminal acetyltransferase A (NatA) complex. acetyl-CoA + N-terminal glycyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetylglycyl-[protein] acetyl-CoA + N-terminal L-alanyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-alanyl-[protein] acetyl-CoA + N-terminal L-seryl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-seryl-[protein] acetyl-CoA + N-terminal L-valyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-valyl-[protein] acetyl-CoA + N-terminal L-cysteinyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-cysteinyl-[protein] acetyl-CoA + N-terminal L-threonyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-threonyl-[protein] Component of the N-terminal acetyltransferase A (NatA) complex composed of NAA11 and NAA15. Interacts with HIF1A. Belongs to the acetyltransferase family. ARD1 subfamily.