Protein‐carbohydrate complementarity in mammalian gamete recognition

Abstract

Recent studies suggest that gamete recognition in a number of species is mediated by complementary proteins and carbohydrates on opposing gamete surfaces. Studies in invertebrates and vertebrates have shown that carbohydrate-binding proteins on the sperm surface recognize and bind to complementary glycoconjugates on the egg's extracellular coat. This chapter reviews our current knowledge of gamete recognition in the mouse. The complementary receptors for both mouse sperm and egg have been identified, purified, and characterized. Their synthesis during gametogenesis has been defined, as have the effects of sperm capacitation and of the acrosome reaction on their expression and distribution. Their relationship to gamete receptors that function in other species is discussed. Finally, evidence is presented that suggests that one of the receptors that mediate mouse gamete recognition belongs to a family of cell surface receptors that function during multiple cellular interactions in development.Key words: acrosome reaction, capacitation, galactosyltransferase, gamete receptors, glycoconjugates, lectins, spermatogenesis, zona pellucida INTRODUCTIONThe binding and union of two separate gametes to form a new organism has intrigued investigators for the last century. In 1913, F.R. Lillie proposed that complementary cell surface receptors mediate gamete recognition and binding [Lillie, 19131, but not until the last 15 years has progress been made toward identifying these receptors.Although the molecular mechanisms underlying gamete recognition and fusion are yet to be clearly resolved, a recurring theme extends throughout several orders of the animal kingdom. It appears that sperm surface carbohydrate-binding proteins mediate gamete recognition by binding with high affinity and specificity to complex glycoconjugates of the egg coat (Fig. 1) species, sperm interactions with the egg coat are species specific. This specificity is attributed to complementarity between interacting molecules on opposing gamete surfaces. It is not surprising that interactions between complementary cell surface proteins and glycoconjugates participate in fertilization, since a number of somatic cells appear to utilize a similar paradigm for intercellular recognition [Damsky et al., 1984; Ivatt, 19841. This chapter will focus primarily on the manner in which glycoconjugate recognition mediates the initial phases of gamete interaction during fertilization. A brief overview is presented to indicate that gamete recognition is mediated in a number of systems by protein-carbohydrate complementarity. To illustrate this concept more fully, the discussion focuses on one of the more thoroughly characterized systems-the mouse. The cell surface molecules that mediate gamete recognition in the mouse have been identified and characterized, as have their expression during gametogenesis and their fate following initial gamete interaction. A brief discussion follows of analogous mechanisms in other species, and in other cellular interactions. PROTEIN: CARBOHYDR...

Binding of Zona Binding Inhibitory Factor-1 (ZIF-1) from Human Follicular Fluid on Spermatozoa

“…It has been shown that sperm carbohydrate-binding proteins bind to glycoconjugates of the zona pellucida in different species and mediate gamete recognition (17)(18)(19). We hypothesize that ZIF-1 exerts its zona binding inhibitory activity via its carbohydrate moieties.…”

Histochemical detection of the lectin-binding carbohydrates in the zona pellucida during oocyte growth in the wild boar (Sus scrofa scrofa)

“…It is involved in species-specific sperm-egg binding, induction of acrosome interaction, post-fertilisation block to polyspermy and embryo protection during its transit along the reproductive tract [7,26,27]. Previous biochemical studies have demonstrated that the glycan portion of the glycoproteins ZPB of the pig [29] and of ZP3 [6,24,28] of the mouse may be the complementary sperm receptors mediating the primary binding between the spermatozoon and the ZP.…”

Identification, Localization and Involvement of Glycosidases in Sperm-Zona Interaction Using Frozen-Thawed Ejaculated Pig Spermatozoa.

“…Generally, lysosomal glycosidases act to catalyze hydrolysis of the terminal glycosidically linked monosaccharide constituents of the oligosaccharide moieties of glycoproteins, glycolipids and glycosaminoglycans (for review see [1]). However, in spermatozoa, glycosidases are thought to form stable enzyme-substrate complexes by binding with high specificity and affinity to the oligosaccharide residues of the glycoproteins of the ZP without acting as a catalyzer (for review see [2]). Many investigators have found various sperm glycosidases such as α-L-fucosidase in cattle [3,4] and rats [5], α-D-mannosidase in rats [6], mice [7] and humans [8], β-D-galactosidase in rabbits [9] and rats [10][11][12] and N-acetyl-β-D-glucosaminidase (GlcNAc'ase) in sheep [13], rats [10], cattle [14], buffaloes and goats [15], mice [16] and pigs [17].…”