Component of the zona pellucida, an extracellular matrix surrounding oocytes which mediates sperm binding, induction of the acrosome reaction and prevents post-fertilization polyspermy (PubMed:29895852). The zona pellucida is composed of 3 to 4 glycoproteins, ZP1, ZP2, ZP3, and ZP4. ZP2 may act as a secondary sperm receptor (PubMed:29895852). . This is the function of ZP2 (zona pellucida glycoprotein 2, Ensembl gene identifier ENSG00000103310).