CHANNELS, RECEPTORS, AND ELECTRICAL SIGNALING |
External K activation of Kir1.1 depends on the pH gate
Henry Sackin 1*, Mikheil Nanazashvili 1, Hui Li 1, Lawrence G. Palmer 2 and D. Eric Walters 1
1 The Chicago Medical School
2 Weill Medical College of Cornell University
* To whom correspondence should be addressed. E-mail: henry.sackin{at}rosalindfranklin.edu.
Submitted on April 3, 2007
Revised on April 25, 2007
Accepted on 27 April 2007
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Abstract |
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The inward rectifier Kir1.1 (ROMK) family is gated by both internal pH and external K, where the putative pH gate is formed by the convergence of leucine side-chains, near the inner helical bundle crossing at L160-Kir1.1. However, it is unclear whether K activation is mediated at the pH gate or by another gate in the permeation path. In the present study, we used the whole-cell conductance increase during rapid K elevation as a measure of K activation, assuming that activation is inherently slower than changes in channel conduction. Results indicate that structural disruption of the Kir1.1 bundle-crossing pH gate prevents both inactivation by low external K and reactivation by high external K.
Key Words:
Kir, KirBac, ROMK, gating, potassium
