ZP2 cleavage blocks polyspermy by modulating the architecture of the egg coat. (https://pubmed.ncbi.nlm.nih.gov/38490181/)

These scientists wanted to understand how a protective layer around an egg, called the zona pellucida, becomes hard after it is fertilized by a sperm. They found that a specific protein in the zona pellucida gets cut into smaller pieces, which causes it to stick together and form a strong structure. This structure is like a double helix, similar to a twisted ladder, made up of different types of proteins. The scientists discovered that this new structure makes the protective layer around the egg very tough, so that other sperms cannot get through after one sperm has fertilized the egg.

Nishio S., Emori C., Wiseman B., Fahrenkamp D., Dioguardi E., Zamora-Caballero S., Bokhove M., Han L., Stsiapanava A., Algarra B., Lu Y., Kodani M., Bainbridge RE., Komondor KM., Carlson AE., Landreh M., de Sanctis D., Yasumasu S., Ikawa M., Jovine L. ZP2 cleavage blocks polyspermy by modulating the architecture of the egg coat. Cell. 2024 Mar 14;187(6):1440-1459.e24. doi: 10.1016/j.cell.2024.02.013.