CD146 belongs to the immunoglobulin super-gene family with five immunoglobulin like domains (V-V-C2-C2-C2), a transmembrane region and a 63 residue cytoplasmic tail. The protein is a membrane glycoprotein that functions as a Ca2+ independent cell adhesion molecule involved in heterophilic cell to cell interactions. CD146 has a molecular size of 130 kDa in its reduced form (118 kDa unreduced), and N linked glycosylation accounts for fifty percent of the apparent molecular weight. In some cells the molecule carries a sulfate 3 glucuronyl moiety.