Oocyte-specific oolemmal receptor involved in sperm and egg adhesion and fertilization. Plays a role in the polyspermy inhibition. Probably acts as a protease for the post-fertilization cleavage of ZP2. Cleaves the sperm-binding ZP2 at the surface of the zona pellucida after fertilization and cortical granule exocytosis, rendering the zona pellucida unable to support further sperm binding. Binds 1 zinc ion per subunit. Inhibited by wide spectrum metalloproteinase inhibitor batimastat (BB-94). Also inhibited by EDTA (By similarity). Interacts (via N-terminal domain) with SPACA3; the interaction occurs during fertilization. Probably exocytosed from cortical granules during post-fertilization. Detected throughout the ooplasm of germinal vesicle stage oocytes in early bilaminar secondary follicles at postnatal (PN) day 3. Detected in the microvillar domain of the oolemma in arrested ovulated secondary oocytes and in the first polar body prior to fertilization. Upon fertilization, detected in the perivitelline space (PVS) and occasionally on the oolemma in 2-cell through morulae stages. Colocalizes with SPACA3 at the microvillar domain of the oolemma and in the perivitelline space (PVS). Ovary-specific. Expressed in secondary, antral and Graafian follicle oocytes. Expressed in the egg cells. Not detected in two-cell embryos. Not detected in naked oocytes, oocytes in primordial or unilaminar primary follicles, or in any other ovarian cells at pre-pubertal, pubertal or adult stages (at protein level). Ovary-specific. Expressed in embryonic stem cells. Absence of cortical granules exocytosis during post-fertilization. Multiple capacitated sperm binding to eggs and two-cell embryos are not prevented. Post-fertilization cleavage of ZP2 does not occur. Life's boundaries - Issue 141 of September 2012