Localization of N-linked carbohydrate chains in glycoprotein ZPA of the bovine egg zona pellucida.
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.
Graduate School of Science and Technology and Department of Chemistry, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba, Japan 263-8522.
Keiichi
K
Ikeda
Naoto
N
Yonezawa
Keita
K
Naoi
Toshiyuki
T
Katsumata
Seizo
S
Hamano
Minoru
M
Nakano
D000595:Amino Acid Sequence; D000818:Animals; D002240:Carbohydrate Sequence; D002417:Cattle; D004527:Egg Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005260:Female; D006020:Glycopeptides / Q000737:chemistry; D006031:Glycosylation; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D011956:Receptors, Cell Surface; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000737:chemistry; D013552:Swine; D015044:Zona Pellucida / Q000737:chemistry*; D000072216:Zona Pellucida Glycoproteins; D001616:beta-Galactosidase / Q000378:metabolism
D004527:Egg Proteins; D006020:Glycopeptides; D008562:Membrane Glycoproteins; D009844:Oligosaccharides; D011956:Receptors, Cell Surface; D000072216:Zona Pellucida Glycoproteins; D001616:beta-Galactosidase