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

Eur J Biochem. 2002 Sep;269(17):4257-66. doi: 10.1046/j.1432-1033.2002.03111.x.

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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

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

Substances

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