Prostate-specific membrane antigen (PSMA), also known as Folate hydrolase 1 (FOLH1), Glutamate carboxypeptidase 2 (GCP2), or N-acetylated-alpha-linked acidic dipeptidase I (ALAD1), is a member of the peptidase M28 family and M28B subfamily. PSMA is stable at pH levels greater than 6.5 and is a type II transmembrane zinc metallopeptidase with high expression in the nervous system, prostate, kidney, and small intestine.
PSMA forms homodimers, binds two zinc ions per subunit, and is required for its ALADase activity. It exhibits catalytic activity involved in the release of an unsubstituted, C-terminal glutamyl residue, typically from sequences such as Ac-Asp-Glu or folylpoly-gamma-glutamates. PSMA possesses both folate hydrolase and N-acetylated-alpha-linked acidic dipeptidase (ALADase) activities, showing a preference for tri-alpha-glutamate peptides.