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Title
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Mammalian gamete fusion depends on the inhibition of ovastacin by fetuin-B.
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Authors
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W.Stöcker,
K.Karmilin,
A.Hildebrand,
H.Westphal,
I.Yiallouros,
R.Weiskirchen,
E.Dietzel,
J.Floehr,
W.Jahnen-Dechent.
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Ref.
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Biol Chem, 2014,
395,
1195-1199.
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PubMed id
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Abstract
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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.
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