Biophys J, May 2001, p. 2216-2220, Vol. 80, No. 5

Revisiting the Role of Ca²⁺ in Shaker K⁺ Channel Gating

Kwang Hee Hong,^* Clay M. Armstrong, and Christopher Miller^*

 ^*Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts 02454, and  Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6085 USA

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 K_v-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.

Biophys J, May 2001, p. 2216-2220, Vol. 80, No. 5
© 2001 by the Biophysical Society   0006-3495/01/05/2216/05  $2.00

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