Experimental and AI-Predicted Structural Analysis Reveals Dynamic Changes in Oocyte Extracellular Matrix：Molecular Mechanisms of Polyspermy Block

Fertilization is the process by which male and female gametes fuse to form a fertilized egg. In mammals and amphibians, polyspermy is lethal. Upon fertilization, egg-derived proteases specifically cleave ZP2, one of the glycoproteins surrounding the oocyte, associated with egg coat hardening. However, the molecular mechanisms and egg coat structure remained unknown. We combined X-ray crystallography, cryo-electron microscopy, and AlphaFold2 structure prediction to elucidate the three-dimensional structure of egg coat matrix formed by ZP glycoprotein polymerization and the molecular mechanisms underlying polyspermy block through egg coat structural changes.