Fig. 7
Model of cortical granule dynamics at the cortex-plasma membrane interface to prevent polyspermy in mouse eggs. MATER anchors cortical granules in the cortex underlying the egg’s plasma membrane where they associate with non-muscle myosin IIA, a motor protein. During fertilization and egg activation, cortical actin is cleared and cortical granules traffic to the plasma membrane. Fusion of cortical granules at the plasma membrane releases their contents, including zinc and the metalloendopeptidase ovastacin, into the extracellular space. These cortical granule contents prevent sperm penetration of the zona matrix and cleave the zona pellucida protein ZP2 to ensure monospermic fertilization
