There are four major zona pellucida glycoproteins, termed ZP1-4. ZP1, ZP3 and ZP4 bind to capacitated spermatozoa and induce the acrosome reaction. Successful fertilization depends on the ability of sperm to penetrate extracellular matrix surrounding eggs. In the mouse:
- ZP3 allows species-specific sperm binding
- ZP2 mediates subsequent sperm binding
- ZP1 cross-links ZP2 and ZP3.
Data with native human protein is not currently available.
Read more about this topic: Zona Pellucida