Summary
A voltage-dependent and Ca2+-activated cation channel found in the vacuolar membrane of the yeast,Saccharomyces cerevisiae, was incorporated into planar lipid bilayer and its gating characteristics were studied at the macroscopic and single-channel levels. The open-channel probability at steady state, which was estimated by the macroscopic current measurement, gave a maximum value at −10 mV and decreased in a graded fashion as the voltage became more positive or more negative. The steady-state voltage dependence was explained by assuming two independent gates, which had different rate constants and opposite voltage dependence. The fast-responding gate opened when the voltage of thecis side (the side to which the vesicles were added) was made more negative and the slow-responding gate behaved in the opposite direction. Relatively high concentrations of Ca2+, about 1mm, were required on thecis side for opening the slow gate in a voltage-dependent manner. DIDS increased the open-channel probability of the fast gate when added to thecis side, but was ineffective on the slow gate.
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Tanifuji, M., Sato, M., Wada, Y. et al. Gating behaviors of a voltage-dependent and Ca2+-activated cation channel of yeast vacuolar membrane incorporated into planar lipid bilayer. J. Membrain Biol. 106, 47–55 (1988). https://doi.org/10.1007/BF01871766
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DOI: https://doi.org/10.1007/BF01871766