A high‐conductance voltage‐dependent multistate Ca2+ channel found in sea urchin and mouse spermatozoa

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Abstract
Ion fluxes through poorly understood channel-mediated mechanisms participate in the interaction between spermatozoa and egg. Previously, we reported the characterization in planar bilayers of a high conductance Ca2+-selective, voltage-dependent multistate channel from S. purpuratus sea urchin sperm plasma membranes [14]. Here we show that this ion channel can be directly transferred to planar lipid bilayers upon sperm addition, from sea urchin [S. purpuratus and L. pictus) and from mouse. We found that spermatozoa from these species posses a conspicuous Ca2+-selective, high conductance, multi-state, voltage-dependent channel, which displays similar voltage dependence and equal PBa2+/PK+ ~4 in the three species. The presence of this Ca2+ channel in such diverse species suggests it plays a relevant role in sperm physiology. The high sensitivity of planar bilayers to detect single ion channels can now be used to study ion channel regulation and gamete interaction