title: Mammalian gamete fusion depends on the inhibition of ovastacin by fetuin-B.
abstract: The zona pellucida, a glycoprotein matrix surrounding the mammalian oocyte, hardens after intrusion of the first spermatozoon, thus protecting the embryo until implantation and preventing multiple fertilizations (polyspermy). Definitive zona hardening is mediated by the metalloprotease ovastacin, which is released from cortical granules of the oocyte upon sperm penetration. However, traces of ovastacin seep from unfertilized eggs to cause zona hardening even in the absence of sperm. These small amounts of protease are inactivated by the plasma protein fetuin-B, thus keeping eggs fertilizable. Once a sperm has penetrated the egg, ovastacin from cortical vesicles overrides fetuin-B and initiates zona hardening.
authors.forename: Walter
authors.initials: W
authors.lastname: Stöcker
authors.forename: Konstantin
authors.initials: K
authors.lastname: Karmilin
authors.forename: André
authors.initials: A
authors.lastname: Hildebrand
authors.forename: Hagen
authors.initials: H
authors.lastname: Westphal
authors.forename: Irene
authors.initials: I
authors.lastname: Yiallouros
authors.forename: Ralf
authors.initials: R
authors.lastname: Weiskirchen
authors.forename: Eileen
authors.initials: E
authors.lastname: Dietzel
authors.forename: Julia
authors.initials: J
authors.lastname: Floehr
authors.forename: Willi
authors.initials: W
authors.lastname: Jahnen-Dechent
mesh_terms: D000818:Animals; D005260:Female; D005298:Fertility; D005306:Fertilization; D060752:Fetuin-B / Q000502:physiology*; D005854:Germ Cells / Q000502:physiology*; D006801:Humans; D045726:Metalloproteases / Q000037:antagonists & inhibitors*; D011247:Pregnancy; D013084:Sperm-Ovum Interactions
chemical_list: D060752:Fetuin-B; D045726:Metalloproteases; C487826:ASTL protein, human