title: A role for carbohydrate recognition in mammalian sperm-egg binding.
abstract: Mammalian fertilization usually requires three sequential cell-cell interactions: (i) initial binding of sperm to the specialized extracellular matrix coating the egg known as the zona pellucida (ZP); (ii) binding of sperm to the ZP via the inner acrosomal membrane that is exposed following the induction of acrosomal exocytosis; and (iii) adhesion of acrosome-reacted sperm to the plasma membrane of the egg cell, enabling subsequent fusion of these gametes. The focus of this review is on the initial binding of intact sperm to the mammalian ZP. Evidence collected over the past fifty years has confirmed that this interaction relies primarily on the recognition of carbohydrate sequences presented on the ZP by lectin-like egg binding proteins located on the plasma membrane of sperm. There is also evidence that the same carbohydrate sequences that mediate binding also function as ligands for lectins on lymphocytes that can inactivate immune responses, likely protecting the egg and the developing embryo up to the stage of blastocyst hatching. The literature related to initial sperm-ZP binding in the three major mammalian models (human, mouse and pig) is discussed. Historical perspectives and future directions for research related to this aspect of gamete adhesion are also presented.
authors: Division of Reproductive and Perinatal Research, Department of Obstetrics, Gynecology and Women's Health, University of Missouri School of Medicine, One Hospital Drive HSC M658, Columbia, MO 65211, USA. Electronic address: clarkgf@health.missouri.edu.
authors: Gary F
authors: GF
authors: Clark
mesh_terms: D000818:Animals; D050260:Carbohydrate Metabolism; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000737:chemistry; D002352:Carrier Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D000080506:Sialyl Lewis X Antigen; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D013552:Swine; D015044:Zona Pellucida / Q000502:physiology
chemical_list: D002241:Carbohydrates; D002352:Carrier Proteins; D009844:Oligosaccharides; D011134:Polysaccharides; D000080506:Sialyl Lewis X Antigen
keywords: Acrosomal exocytosis; Fertilization; Oligosaccharide; Sialyl-Lewis(x); Species recognition system; Zona pellucida