Probable oocyte-specific oolemmal receptor involved in sperm and egg adhesion and fertilization (By similarity). Protease which may play a role in the breaking down of the vitelline membrane (days 0-5) and possibly, in the digestion of the egg white (days 9-12) (PubMed:16003522). Binds 1 zinc ion per subunit. Expressed in ectodermal cells of the yolk sac during epiboly on days 0 - 5 (PubMed:16003522). Expressed in ectodermal cells of the albumen sac on days 8 - 13 (PubMed:16003522). By 1,25-dihydroxyvitamin D-3. Minor transcript.