Abstract
Fertilization occurs after the completion of the sperm acrosome reaction, a secretory event that is triggered during gamete adhesion. ZP3, an egg zona pellucida glycoprotein, produces a sustained increase of the internal Ca(2+) concentration in mouse sperm, leading to acrosome reactions. Here we show that the sustained Ca(2+) concentration increase is due to the persistent activation of a Ca(2+) influx mechanism during the late stages of ZP3 signal transduction. These cells also possess a Ca(2+) store depletion-activated Ca(2+) entry pathway that is open after treatment with thapsigargin. Thapsigargin and ZP3 activate the same Ca(2+) permeation mechanism, as demonstrated by fluorescence quenching experiments and by channel antagonists. These studies show that ZP3 generates a sustained Ca(2+) influx through a store depletion-operated pathway and that this drives the exocytotic acrosome reaction.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Acrosome Reaction / drug effects
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Acrosome Reaction / physiology*
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Animals
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Calcium / metabolism*
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Calcium Channel Blockers / pharmacology
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Calcium Channels / metabolism*
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Calcium Signaling
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Chelating Agents / pharmacology
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Egg Proteins / metabolism*
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Egtazic Acid / analogs & derivatives
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Egtazic Acid / pharmacology
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Female
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Ionomycin / pharmacology
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Ionophores / pharmacology
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Male
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Manganese / metabolism
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Manganese / pharmacology
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Membrane Glycoproteins / metabolism*
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Mice
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Mice, Inbred Strains
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Receptors, Cell Surface*
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Sperm Capacitation
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Spermatozoa / drug effects
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Spermatozoa / metabolism*
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Spermatozoa / physiology
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Thapsigargin / pharmacology
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Verapamil / pharmacology
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Zona Pellucida Glycoproteins
Substances
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Calcium Channel Blockers
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Calcium Channels
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Chelating Agents
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Egg Proteins
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Ionophores
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Membrane Glycoproteins
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Receptors, Cell Surface
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Zona Pellucida Glycoproteins
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Zp3 protein, mouse
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Manganese
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Egtazic Acid
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Ionomycin
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Thapsigargin
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Verapamil
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1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
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Calcium