(UroToday.com) Prostate membrane antigen (PSMA) is a type 2 transmembrane protein with an enzymatic function of a folate hydrolase carboxypeptidase. It is expressed in several tissues with different functions, including activity in Glial cells, modulating signal transduction pathway, in the small intestine, assisting in fulling absorption, and it has an uncertain role in the prostate (figure 1).