Structural relationships between the isoenzymes of human placental alkaline phosphatase: a serum factor converts M-PLAP to A- and B-PLAP.

ABSTRACT

A protein factor has been found in serum which converts the M form of placental alkaline phosphatase (PLAP) to the A and B forms. The identity of the conversion products has been confirmed by analysis of their dimers and polypeptides. Proteolysis is not implicated in this phenomenon. This report establishes microvillous M-PLAP as the precursor of the A and B forms.