Localization of N-linked carbohydrate chains in glycoprotein ZPA of the bovine egg zona pellucida.

Abstract

The zona pellucida, a transparent envelope surrounding the mammalian oocyte, consists of three glycoproteins, ZPA, ZPB and ZPC, and plays a role in sperm-egg interactions. In bovines, these glycoproteins cannot be separated unless the acidic N-acetyllactosamine regions of the carbohydrate chains are removed by endo-beta-Galactosidase digestion. Endo-beta-Galactosidase-digested ZPB retains stronger sperm-binding activity than ZPC. It is still unclear whether ZPA possesses significant activity. Recently, we reported that bovine sperm binds to Man5GlcNAc2, the neutral N-linked chain in the cow zona proteins. In this study, we investigated the localization of the sperm-ligand active high-mannose-type chain and the acidic complex-type chains in bovine ZPA. Three N-glycopeptides of ZPA, containing an N-glycosylation site at Asn83, Asn191 and Asn527, respectively, were obtained from endo-beta-Galactosidase-digested ZPA. Of these glycosylation sites, only Asn527 is present in the ZP domain common to all the zona proteins. The carbohydrate structures of the N-linked chains obtained from each N-glycopeptide were characterized by two-dimensional sugar mapping analysis, while considering the structures of the N-linked chains of the zona protein mixture reported previously. Acidic complex-type chains were found at all three N-glycosylation sites, while Man5GlcNAc2 was found at Asn83 and Asn191, but there was very little of this sperm-ligand active chain at Asn527 in the ZP domain of ZPA.

• Authors: Keiichi Ikeda, Naoto Yonezawa, Keita Naoi, Toshiyuki Katsumata, Seizo Hamano, Minoru Nakano
• Journal: European journal of biochemistry (Eur J Biochem) Vol. 269 Issue 17 Pg. 4257-66 (Sep 2002) ISSN: 0014-2956 [Print] England
• PMID: 12199704 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Egg Proteins
• Glycopeptides
• Membrane Glycoproteins
• Oligosaccharides
• Receptors, Cell Surface
• Zona Pellucida Glycoproteins
• beta-Galactosidase

Topics

• Amino Acid Sequence
• Animals
• Carbohydrate Sequence
• Cattle
• Egg Proteins (chemistry, genetics, metabolism)
• Female
• Glycopeptides (chemistry)
• Glycosylation
• Male
• Membrane Glycoproteins (chemistry, genetics, metabolism)
• Molecular Sequence Data
• Oligosaccharides (chemistry)
• Receptors, Cell Surface
• Sperm-Ovum Interactions
• Spermatozoa (chemistry)
• Swine
• Zona Pellucida (chemistry)
• Zona Pellucida Glycoproteins
• beta-Galactosidase (metabolism)