Neuron
Volume 15, Issue 5, November 1995, Pages 1157-1168
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Identification and molecular localization of a pH-sensing domain for the inward rectifier potassium channel HIR

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Abstract

Inward rectifier potassium channels are found in the heart and CNS, where they are critical for the modulation and maintenance of cellular excitability. We present evidience that the inward rectifier potassium channel HIR is modulated by extracellular pH in the physiological rante. We show that proton-induced changes in HIR single-channel conductance underline the HIR pH sensitivity seen on the macroscopic level. We used chimeric and mutant channels to localize the molecular determinant of HIR pH sensitivity to a single residue, H117, in the M1-to-H5 linker region. This residue provides a molecular context that allows a titratable group to influence pore proterties. We present evidence that this titratable group is one of two cysteines located in the M1-to-H5 and H5-to-M2 linkers.

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These authors contributed equally to this work.