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

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 Ca(2+)-selective, voltage-dependent multistate channel from S. purpuratus sea urchin sperm plasma membranes. 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 possess a conspicuous Ca(2+)-selective, high conductance, multi-state, voltage-dependent channel, which displays similar voltage dependence and equal PBa2+/PK+ approximately 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.