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Ca2+ channels from the sea urchin sperm plasma membrane
A Liévano1, E C Vega-SaenzdeMiera, A Darszon
1Departamento de Bioquimica, Centro de Investigación y de Estudios Avanzados del IPN, México, DF.
The Journal of General Physiology
|February 1, 1990
Summary
Researchers identified a novel calcium channel in sea urchin sperm crucial for the acrosome reaction. This channel
Area of Science:
- * Marine Biology
- * Cell Physiology
- * Ion Channel Research
Background:
- * Calcium influx is essential for sea urchin sperm acrosome reaction.
- * Direct demonstration of calcium channels in these cells is challenging due to their small size.
Purpose of the Study:
- * To directly identify and characterize calcium channels in sea urchin sperm.
- * To investigate the properties of these channels using electrophysiological methods.
Main Methods:
- * Fusion of isolated sea urchin sperm plasma membranes into planar lipid bilayers.
- * Single-channel recording and analysis of ion flux.
- * Voltage-clamp experiments to determine channel conductance and ion selectivity.
Main Results:
- * A novel calcium channel was detected with high main-state conductance (172 pS in 50 mM CaCl2).
- * The channel is blocked by Cd2+, Co2+, and La3+, and shows selectivity for Ba2+ > Sr2+ > Ca2+.
- * Voltage-dependent gating and poor discrimination between divalent and monovalent cations were observed.
Conclusions:
- * A novel, Ca2+-selective channel in sea urchin sperm has been characterized.
- * Findings suggest this channel plays a critical role in the acrosome reaction and may function as a multipore assembly.