Interactions between mouse ZP2 glycoprotein and proacrosin: A mechanism for secondary binding of sperm to the zona pellucida during fertilization

The experiments presented above give direct evidence that mouse sperm β-acrosin is a major binding protein (secondary ligand) for ZP2, one of the three sulfated glycoproteins that constitute the ZP around mouse eggs. The authors suggest that suramin, which competes strongly with ZP2 for binding sites on proacrosin/β-acrosin, represents a stereochemically similar sulfated structure on ZP2, possibly a sulfated oligosaccharide.