This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this book Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Miller, D. J. Articles by Burkin, H. Search for Related Content PubMed PubMed Citation Articles by Miller, D. J. Articles by Burkin, H.

Molecular Basis of Mammalian Gamete Binding

Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801

Despite the importance of fertilization for controlling human reproduction, regulating animal production, and promoting preservation of endangered species, the molecular basis underlying gamete binding and fertilization has been perplexing. More progress has been made in the mouse than in other mammals and, recently, targeted deletion of specific genes in the mouse has yielded intriguing results. This review will emphasize research performed by our laboratory and others done primarily with mouse gametes but will include some interesting observations from other mammals. Studies of murine fertilization indicate that oligosaccharides on the egg coat glycoprotein ZP3 bind sperm. The precise oligosaccharides that bind sperm are the subject of considerable debate. ZP3 also induces exocytosis of the sperm acrosome, allowing sperm to penetrate through the egg coat (zona pellucida). A number of candidate ZP3 receptors have been proposed and studies of ß1,4galactosyltransferase-I (GalT-I) are reviewed here in the most detail. Sperm from mice with a targeted deletion of GalT-I still are able to bind the zona pellucida but are unable to acrosome react and penetrate through the zona. Therefore, the unique role of GalT-I appears to be in signal transduction. GalT-I forms a complex with heterotrimeric G proteins and activates signaling, leading to exocytosis in sperm and in heterologous cells expressing GalT-I. Other signaling steps triggered by GalT-I are under active investigation; this receptor forms a complex with a protein kinase anchoring protein. After exocytosis of the acrosome, sperm penetrate the zona pellucida and fuse with the oocyte plasma membrane using ADAM family members on sperm and integrins on oocytes. These proteins, along with the tetraspanins on oocytes, may form a complex web at gamete fusion. Targeted deletion of specific genes in this putative complex has provided important information about their redundancy. After the oocyte is fertilized, the binding site for GalT-I is lost from ZP3, preventing additional sperm from binding to the zona pellucida. New technical advances and creative ideas offer the opportunity to make important advances and to solve the conundrum of fertilization.

This article has been cited by other articles:

				S. Canovas, R. Romar, L. A. Grullon, M. Aviles, and P. Coy Pre-fertilization zona pellucida hardening by different cross-linkers affects IVF in pigs and cattle and improves embryo production in pigs Reproduction, May 1, 2009; 137(5): 803 - 812. [Abstract] [Full Text] [PDF]

				S. Canovas, P. Coy, and E. Gomez First Steps in the Development of a Functional Assay for Human Sperm Using Pig Oocytes J Androl, March 1, 2007; 28(2): 273 - 281. [Abstract] [Full Text] [PDF]

				G. F. Doncel Exploiting common targets in human fertilization and HIV infection: development of novel contraceptive microbicides Hum. Reprod. Update, March 1, 2006; 12(2): 103 - 117. [Abstract] [Full Text] [PDF]

				Y. Shen, T. Stalf, C. Mehnert, U. Eichenlaub-Ritter, and H.-R. Tinneberg High magnitude of light retardation by the zona pellucida is associated with conception cycles Hum. Reprod., June 1, 2005; 20(6): 1596 - 1606. [Abstract] [Full Text] [PDF]

				K. Bogner, K.-D. Hinsch, P. Nayudu, L. Konrad, C. Cassara, and E. Hinsch Localization and synthesis of zona pellucida proteins in the marmoset monkey (Callithrix jacchus) ovary Mol. Hum. Reprod., July 1, 2004; 10(7): 481 - 488. [Abstract] [Full Text] [PDF]