Biochemical studies of human syncytiotrophoblastic plasma membrane proteins

Interest in the structure and function of the human syncytiotrophoblastic plasma membrane has been stimulated by the possibility that it may contribute to the acceptance of the foetal allograft. Preparations enriched in syncytiotrophoblastic plasma membrane microvilli have been isolated and their polypeptide composition analysed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. Extrinsic membrane proteins were identified by extraction with 3 M KC1 and intrinsic membrance proteins were identified by solubilization of KC1-extracted membranes with the detergent sodium deoxycholate. A number of glycoproteins were isolated from detergent-solubilized syncytiotrophoblast membranes by absorption with wheat germ lectin-Sepharose followed by elution with N-acetyl-D-glucosamine, Since these glycoproteins are swept into the maternal blood during trophoblast deportation, methods for their isolation and characterization are necessary to describe more completely this aspect of materno-foetal immunobiology. The results presented here provide another step towards this goal.