PMSA (FOLH1) is a type II transmembrane glycoprotein belonging to the M28 peptidase family. Three functionally distinct proteins are encoded, including folylpoly-gamma-glutamate carboxypeptidase in the intestine, N-acetylated alpha-linked acidic dipeptidase 1 in the brain, and prostate-specific membrane antigen in the prostate. A mutation in the intestinal form may be associated with impaired intestinal absorption of dietary folates, resulting in low blood folate levels and consequent hyperho