Revisiting the role of Ca2+ in Shaker K+ channel gating |
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| Authors: | Hong K H Armstrong C M Miller C |
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| Affiliation: | Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts 02454, USA. |
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| Abstract: | Shaker K+ channels were expressed in outside-out macropatches excised from Xenopus oocytes, and the effects on gating of removal of extracellular Ca2+ were examined in the complete absence of intracellular divalent cations. Removal of extracellular Ca2+ by perfusion with EDTA-containing solution caused a small negative shift in the channel's voltage-activation curve and led to an increased nonselective leak, but did not otherwise alter or disrupt the channels. The results contradict the proposal that Ca2+ is an essential component required for maintenance of ion selectivity and proper gating of Kv-type K+ channels. The large nonselective leak in Ca2+-free conditions was found to be a patch-seal phenomenon related to F- ion in the recording pipette. |
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