A hybrid form of alkaline phosphatase produced in FL-amnion cells.

FL-amnion cells have mainly two alkaline phosphatase (AP) isozymes, of which the faster migrating one (FL-APF) on 5% polyacrylamide gel electrophoresis has proved to be identical to the Kasahara isozyme, a tumor-associated AP of intestinal type. But the other slower migrating one (FL-APs) remains to be characterized. Immunological and enzymic examination of purified FL-APs revealed that it is a hybrid form of AP consisting of one subunit with a molecular weight of 66,200 coming from the same subunit as that of FL-APF and another one with a molecular weight of 58,000 from placental AP subunit with modified glycosylation.