Prostate specific membrane antigen (PSMA), also known as Glutamate carboxypeptidase II (GCPII), is a type II transmembrane glycoprotein that belongs to the M28 peptidase family. It acts as a glutamate carboxypeptidase on different substrates such as folate as well as the neuropeptide N-acetyl-l-aspartyl-l-glutamate. PSMA is expressed in a number of tissues including prostate, kidney, and both the central and peripheral nervous systems.