| Literature DB >> 1555592 |
Abstract
Affinity chromatography of human plasma on placental-alkaline-phosphatase-Sepharose columns (placental alkaline phosphatase, PLAP) yielded consistently a pure protein which was identified as IgG on the basis of electrophoretical and immunological comparisons with authentic human IgG. SDS/PAGE of the protein revealed, under reducing conditions, two polypeptides of 55 kDa and 25 kDa. The N-terminal amino acid sequence (12 residues) of the 55-kDa subunit presented high similarity (83-100%) with known sequences of immunoglobulin gamma chains. The IgG binds by its Fc portion to a fully exposed domain in the plasma-membrane-anchored PLAP. Scatchard analysis of the interaction gave a dissociation constant of 3.68 microM, a value close to those found for haematopoietic cells and syncytiotrophoblast Fc receptors. The latter was affinity purified from human placenta as the major IgG-binding component and presented cross-immunoreactivity with anti-PLAP antibodies, indicating that PLAP and the putative placental Fc receptor could be identical molecules.Entities:
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Year: 1992 PMID： 1555592 DOI： 10.1111/j.1432-1033.1992.tb16785.x
Source DB: PubMed Journal: Eur J Biochem ISSN： 0014-2956