Component of the zona pellucida, an extracellular matrix surrounding oocytes which mediates sperm binding, induction of the acrosome reaction and prevents post-fertilization polyspermy. The zona pellucida is composed of 3 to 4 glycoproteins, ZP1, ZP2, ZP3, and ZP4. ZP1 ensures the structural integrity of the zona pellucida. Polymers of ZP2 and ZP3 organized into long filaments cross-linked by ZP1 homodimers (By similarity). Interacts with ZP3 (PubMed:28886344). Expressed in oocytes (at protein level). The ZP domain is involved in the polymerization of the ZP proteins to form the zona pellucida. Proteolytically cleaved before the transmembrane segment to yield the secreted ectodomain incorporated in the zona pellucida. O-glycosylated. The disease is caused by variants affecting the gene represented in this entry. Belongs to the ZP domain family. ZPB subfamily.