Ion channel activity of membrane vesicles released from sea urchin sperm during the acrosome reaction

The sperm acrosome reaction (AR) involves ion channel activation. In sea urchin sperm, the AR requires Ca 2+ and Na + influx and K + and H + efflux. During the AR, the plasma membrane fuses with the acrosomal vesicle membrane forming hybrid membrane vesicles that are released from sperm into the med...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 2004-08, Vol.321 (1), p.88-93
Main Authors: Schulz, Joseph R., De La Vega-Beltrán, Jose L., Beltrán, Carmen, Vacquier, Victor D., Darszon, Alberto
Format: Article
Language:English
Subjects:
Acrosome reaction
Acrosome Reaction - physiology
Acrosome reaction vesicles
Animals
Biomarkers - analysis
Cell Membrane - drug effects
Cell Membrane - physiology
Cyclic AMP - pharmacology
Exocytosis
Fertilization
Ion Channels - drug effects
Ion Channels - physiology
Lipid Bilayers
Male
Membrane Potentials
Membrane Proteins - analysis
Nerve Tissue Proteins - analysis
Permeability
Planar bilayers
Potassium - metabolism
Sea urchin sperm
Sea Urchins
Sodium - metabolism
Sperm ion channels
Spermatozoa - physiology
Synaptosomal-Associated Protein 25
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Summary:The sperm acrosome reaction (AR) involves ion channel activation. In sea urchin sperm, the AR requires Ca 2+ and Na + influx and K + and H + efflux. During the AR, the plasma membrane fuses with the acrosomal vesicle membrane forming hybrid membrane vesicles that are released from sperm into the medium. This paper reports the isolation and preliminary characterization of these acrosome reaction vesicles (ARVs), using synaptosome-associated protein of 25 kDa (SNAP-25) as a marker. Isolated ARVs have a unique protein composition. The exocytosis regulatory proteins vesicle-associated membrane protein and SNAP-25 are inside ARVs, as judged by protease protection experiments, and membrane associated based on Triton X-114 partitioning. ARVs fused with planar bilayers display three main types of single channel activity. The most frequently recorded channel is cationic, weakly voltage dependent and has a low open probability that increases with negative potentials. This channel is activated by cAMP, blocked by Ba 2+, and has a PK +/PNa + selectivity of 4.5. ARVs represent a novel membrane preparation suitable to deepen our understanding of ion channel activity in the AR and during fertilization.
ISSN:0006-291X
1090-2104
DOI:10.1016/j.bbrc.2004.06.109