Anti-pepsinogen A4 antibodies are used for the immunodetection of the protein encoded by the PGA4 gene. In humans, the canonical protein has a reported length of 388 amino acid residues and a mass of 42 kDa. It is known to be a secreted protein. A member of the Peptidase A1 protein family, it is known to be involved with proteolysis. Other names for this target antigen include pepsinogen 4, group I (pepsinogen A), pepsinogen-4, pregnancy-associated glycoprotein, and pepsin A-4.