The role of carbohydrate residues in mammalian fertilization.
The fertilization process in mammals involves binding and fusion of free-swimming sperm and ovulated eggs. This review focuses on the role of carbohydrate residues in the process of sperm-egg interaction in mammals. The zona pellucida (ZP), the acellular glycoprotein coat surrounding the egg is highly glycosylated and possess both Asn- (N-) linked and Ser/Thr- (O-)linked oligosaccharides, with an extreme structural heterogeneity between the different species. Different carbohydrates on ZP3, such as Galactose in alpha-linkage, N-acetylglucosamine in beta-linkage, were suggested as the complementary sperm receptors, mediating the primary binding between the spermatozoon and the ZP. Several suggested complementary ZP3 binding proteins on the sperm are sp56, beta-1,4-galactosyltransferase and p95. Some carbohydrate residues of the ZP undergo post-fertilization modifications that might alter the sperm receptor, thus assisting in the establishment of the block to polyspermy. The studies summarized in this review imply a main role for the carbohydrate residues in the process of sperm egg interaction.
Shalgi
R
R
Department of Embryology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel.
Raz
T
T
D000818:Animals; D002241:Carbohydrates / Q000502:physiology*; D004527:Egg Proteins / Q000378:metabolism; D005260:Female; D005306:Fertilization / Q000502:physiology*; D006801:Humans; D008297:Male; D008322:Mammals; D008562:Membrane Glycoproteins / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000378:metabolism / Q000648:ultrastructure; D015044:Zona Pellucida / Q000737:chemistry* / Q000502:physiology*; D000072216:Zona Pellucida Glycoproteins
D002241:Carbohydrates; D004527:Egg Proteins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C000606517:ZP3 protein, human; D000072216:Zona Pellucida Glycoproteins