Actin maturation protease that specifically mediates the cleavage of immature acetylated N-terminal actin, thereby contributing to actin maturation (PubMed:36173861). Cleaves N-terminal acetylated methionine of immature cytoplasmic beta- and gamma-actins ACTB and ACTG1 after translation (PubMed:36173861). Cleaves N-terminal acetylated cysteine of muscle alpha-actins ACTA1, ACTC1 and ACTA2 after canonical removal of N-terminal methionine (By similarity).