DPEP3 encodes a membrane-bound glycoprotein from the family of dipeptidases (EC 3.4.13.19) involved in hydrolytic metabolism of various dipeptides, including penem and carbapenem beta-lactam antibiotics. This gene is located on chromosome 16 in a cluster with another member of this family, DPEP2. The deduced 493-amino acid mouse protein contains several residues conserved among MBDs, including 6 cysteines, 3 histidines, and a glutamic acid that is important for catalytic activity. Mouse and human MBD3 share 68% amino acid identity. Northern blot analysis detected an Mbd2 RNA in mouse testis only. Phospholipase treatment released Mbd3 from transfected COS-7 cell membranes, indicating that Mbd3 is anchored to the membrane through glycosylphosphatidylinositol modification.