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Biophysical Journal
Article
License: Elsevier Non-Commercial
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Biophysical Journal
Article . 2015
License: Elsevier Non-Commercial
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Biophysical Journal
Article . 2015 . Peer-reviewed
License: Elsevier Non-Commercial
Data sources: Crossref
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Sequence of Gating Charge Movement and Pore Gating in hERG Activation and Deactivation Pathways

Authors: Logan C. Macdonald; David Fedida; Samuel J. Goodchild;

Sequence of Gating Charge Movement and Pore Gating in hERG Activation and Deactivation Pathways

Abstract

KV11.1 voltage-gated K(+) channels are noted for unusually slow activation, fast inactivation, and slow deactivation kinetics, which tune channel activity to provide vital repolarizing current during later stages of the cardiac action potential. The bulk of charge movement in human ether-a-go-go-related gene (hERG) is slow, as is return of charge upon repolarization, suggesting that the rates of hERG channel opening and, critically, that of deactivation might be determined by slow voltage sensor movement, and also by a mode-shift after activation. To test these ideas, we compared the kinetics and voltage dependence of ionic activation and deactivation with gating charge movement. At 0 mV, gating charge moved ∼threefold faster than ionic current, which suggests the presence of additional slow transitions downstream of charge movement in the physiological activation pathway. A significant voltage sensor mode-shift was apparent by 24 ms at +60 mV in gating currents, and return of charge closely tracked pore closure after pulses of 100 and 300 ms duration. A deletion of the N-terminus PAS domain, mutation R4AR5A or the LQT2-causing mutation R56Q gave faster-deactivating channels that displayed an attenuated mode-shift of charge. This indicates that charge movement is perturbed by N- and C-terminus interactions, and that these domain interactions stabilize the open state and limit the rate of charge return. We conclude that slow on-gating charge movement can only partly account for slow hERG ionic activation, and that the rate of pore closure has a limiting role in the slow return of gating charges.

Keywords

ERG1 Potassium Channel, Patch-Clamp Techniques, Xenopus, Biophysics, Ether-A-Go-Go Potassium Channels, Membrane Potentials, Kinetics, Mutation, Oocytes, Animals, Humans, Ion Channel Gating

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citations
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
21
Top 10%
Average
Top 10%
hybrid