Anti-AC45 antibodies enable researchers to detect and measure the AC45 antigen in biological samples. This target is a reported synonym of the ATP6AP1 gene, which encodes ATPase H+ transporting accessory protein 1. This protein is reported to be an accessory subunit the proton-transporting vacuolar (V)-ATPase protein pump, which is required for luminal acidification of secretory vesicles. The human version of AC45 has a canonical amino acid length of 470 residues and a protein mass of 52 kilodaltons. It is reported to be localized in the cytoplasmic vesicles and ER of cells and widely expressed in many tissue types. Other names for this target antigen include 16A, ATP6IP1, and ATP6S1.