Structural and Functional Analysis of glycoproteins participating in the mammalian fertilization and development

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1) Binding of porcine and bovine sperm to glycolipid analogues We prepared plastic plates to which six kinds of glycolipid analogues having a monosaccharide at the end of alkyl chain are attached. To these plates, porcine or bovine sperm were added. After washing the plates, the numbers of residual sperm were counted. By this method, it was revealed that porcine sperm mainly bind to β-galactose residue of the glycolipid analogue, while bovine sperm to α-mannose residue. Furthermore, the acrosome-reacted sperm of both species bind to α-mannose residue.2) Binding of porcine and bovine sperm to the egg zona pellucida It is universally accepted that sperm species-specifically bind to the zona pellucida. Here we investigated whether porcine and bovine sperm bind to the zona pellucida of heterologous egg. As a result, it was shown that almost the same number of the sperm bound to the heterologous zona as that of the homologous sperm did, reflecting the distribution of the carbohydrate chains on the surface of the zona.3) The binding activity of recombinant zona pellucida glycoproteins to sperm Three zona glycoprotein components (ZPA, ZPB, ZPC) and their combinations were expressed in Sf9 cells and the binding activities of the recombinants to porcine and bovine sperm were analyzed. Since the high-mannose type chains are attached to the proteins by this expression system, the recombinants were bound not to porcine sperm but to bovine sperm. Any single component was not bound to bovine sperm and ZPB/ZPC coexpressed was bound.4) Determination of the carbohydrate structure of glycoproteins expressed at pregnancy The structure of main N-linked chain of bovine pregnancy associated glycoproteins was determined. The N-glycan has an unusual structure having GalNAc.