Abstract
The egg envelope of most animal eggs is modified following fertilization, resulting in the prevention of polyspermy and hardening of the egg envelope. In frogs and mammals a prominent feature of envelope modification is N-terminal proteolysis of the envelope glycoprotein ZPA. We have purified the ZPA protease from Xenopus laevis eggs and characterized it as a zinc metalloprotease. Proteolysis of isolated egg envelopes by the isolated protease resulted in envelope hardening. The N-terminal peptide fragment of ZPA remained disulfide bond linked to the ZPA glycoprotein moiety following proteolysis. We propose a mechanism for egg envelope hardening involving ZPA proteolysis by an egg metalloprotease as a triggering event followed by induction of global conformational changes in egg envelope glycoproteins.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Animals
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Antibodies / chemistry
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Blotting, Western
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Cloning, Molecular
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DNA, Complementary / metabolism
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Egg Proteins / chemistry*
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Electrophoresis, Polyacrylamide Gel
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Enzyme Inhibitors / pharmacology
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Female
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Fertilization
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Male
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Membrane Glycoproteins / chemistry*
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Metalloproteases / metabolism
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Ovum / metabolism
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Peptide Hydrolases / chemistry
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Protease Inhibitors / pharmacology
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Protein Structure, Tertiary
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Proteins / chemistry
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Receptors, Cell Surface / chemistry*
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Spermatozoa / metabolism
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Temperature
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Xenopus laevis
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Zona Pellucida / chemistry*
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Zona Pellucida / metabolism
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Zona Pellucida Glycoproteins
Substances
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Antibodies
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DNA, Complementary
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Egg Proteins
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Enzyme Inhibitors
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Membrane Glycoproteins
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Protease Inhibitors
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Proteins
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Receptors, Cell Surface
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Zona Pellucida Glycoproteins
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Metalloproteases
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Peptide Hydrolases