Anti-PEP antibodies enable researchers to detect and measure the PEP antigen in biological samples. This target is a reported synonym of the PREP gene, which encodes prolyl endopeptidase. This protein is known to function in proteolysis, among other biological roles. The human version of PEP has a canonical amino acid length of 710 residues and a protein mass of 80.7 kilodaltons. It is reported to be localized in the cytoplasm of cells and widely expressed in many tissue types. PEP is a member of the Peptidase S9A protein family.