Localization of neutral N-linked carbohydrate chains in pig zona pellucida glycoprotein ZPC.
Zona pellucida, a transparent envelope surrounding the mammalian oocyte, plays important roles in fertilization and consists of three glycoproteins; ZPA, ZPB and ZPC. In pig, neutral complex-type N-linked chains obtained from a ZPB/ZPC mixture possess sperm-binding activity. We have recently reported that among neutral N-linked chains triantennary and tetraantennary chains have a sperm-binding activity stronger than that of diantennary chains. Triantennary and tetraantennary chains are localized at the second of the three N-glycosylation sites of ZPB. In this study, we focused on the localization of neutral N-linked chains in ZPC. ZPB and ZPC can not be separated from each other unless the acidic N-acetyllactosamine regions of their carbohydrate chains are removed by endo-beta-galactosidase digestion. A large part of the acidic N-linked chains becomes neutral by the digestion, but the main neutral N-linked chains are not susceptible to the enzyme. N-glycanase digestion indicated that ZPC has three N-glycosylation sites. Three glycopeptides each containing one of the N-glycosylation sites were obtained by tryptic digestion of ZPC and the N-glycosylation sites were revealed as Asn124, Asn146 and Asn271. The carbohydrate structures of the neutral N-linked chains from each glycopeptide were characterized by two-dimensional sugar mapping analysis taking into consideration the structures of the main, intact neutral N-linked chains of ZPB/ZPC mixture reported previously. Triantennary and tetraantennary chains were found mainly at Asn271 of ZPC, whereas diantennary chains were present at all three N-glycosylation sites. Thus, ZPC has tri-antennary and tetra-antennary chains as well as ZPB, but the localization of the chains is different from that in ZPB.
Yonezawa
N
N
Graduate School of Science and Technology, Chiba University, Japan.
Fukui
N
N
Kudo
K
K
Nakano
M
M
D000581:Amidohydrolases / Q000378:metabolism; D000818:Animals; D002240:Carbohydrate Sequence; D004527:Egg Proteins / Q000737:chemistry*; D005260:Female; D006020:Glycopeptides / Q000737:chemistry; D006026:Glycoside Hydrolases; D006031:Glycosylation; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry; D009865:Oocytes / Q000737:chemistry; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D011956:Receptors, Cell Surface; D013552:Swine; D014357:Trypsin / Q000378:metabolism; 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; D006026:Glycoside Hydrolases; C026093:keratan-sulfate endo-1,4-beta-galactosidase; D001616:beta-Galactosidase; D014357:Trypsin; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase