Towards the molecular basis of sperm and egg interaction during mammalian fertilization.
During the past 2 decades, a number of genes have been cloned from mammals which encode polypeptides that participate in the process of fertilization. Among these are glycoproteins ZP1-3 that constitute the zona pellucida of eggs from mice to human beings. In mice, one of these glycoproteins, mZP3, acts as a primary sperm receptor and acrosome reaction-inducer. The evidence suggests that acrosome-intact sperm recognize and bind to a specific class of mZP3 oligosaccharides present on two serine residues (O-linked) located near the carboxy-terminus of the polypeptide. Mutagenesis of either of these residues results in the synthesis of an inactive form of the receptor. Therefore, mammalian fertilization is a carbohydrate-mediated event. It is possible that changes in the structure of these oligosaccharides (e.g., composition, sequence, linkages, modifications, etc.) could account for species-specific binding of sperm to eggs. Stably transfected somatic cells, null mutant animals, and DNA constructs are now available to test this possibility both in vivo and in vitro.
Wassarman
P M
PM
Department of Biochemistry and Molecular Biology, Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
Litscher
E S
ES
D020101:Acrosome Reaction / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D004527:Egg Proteins / Q000235:genetics*; D005260:Female; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D008297:Male; D008322:Mammals; D008562:Membrane Glycoproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D011956:Receptors, Cell Surface; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D000072216:Zona Pellucida Glycoproteins
D004527:Egg Proteins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C000606514:ZP1 protein, human; D000072216:Zona Pellucida Glycoproteins; C000606519:Zp1 protein, mouse