PLAP is a tissue specific, trophoblast-derived, 70kDa, glycosyl-phosphatidylinositol (GPI)-anchored, dimeric, Zn2+ metallo-glycoprotein that catalyzes the hydrolysis of phosphomonoesters into an inorganic phosphate and an alcohol. It is present in the placenta and serum of pregnant women and in high frequency in gynecological and testicular cancers and in lower frequency in other tumors. The three tissue-specific APs in humans, PLAP, germ cell AP (GCAP) and intestinal AP, are 90-98% homologous. Non-tissue specific AP is found in kidney, liver and bone. This MAb binds equally well to all common allelic variants (S, F, FS and I) of PLAP and to some variants of AP from normal human testis. This MAb can be used as tracer antibody in ELISA to detect PLAP in serum of S, F, FS and I phenotypes.
