We are seeing patients in-person and through Video Visits. Learn more about how we’re keeping you safe and please review our updated visitor policy. Please also consider supporting Weill Cornell Medicine’s efforts to support our front-line workers.
Department of Anesthesiology

You are here

Calcium-dependent gating of MthK, a prokaryotic potassium channel.

TitleCalcium-dependent gating of MthK, a prokaryotic potassium channel.
Publication TypeJournal Article
Year of Publication2006
AuthorsZadek B, Nimigean CM
JournalJ Gen Physiol
Volume127
Issue6
Pagination673-85
Date Published2006 Jun
ISSN0022-1295
KeywordsArchaeal Proteins, Calcium, Ion Channel Gating, Methanobacterium, Potassium Channels
Abstract

MthK is a calcium-gated, inwardly rectifying, prokaryotic potassium channel. Although little functional information is available for MthK, its high-resolution structure is used as a model for eukaryotic Ca(2+)-dependent potassium channels. Here we characterize in detail the main gating characteristics of MthK at the single-channel level with special focus on the mechanism of Ca(2+) activation. MthK has two distinct gating modes: slow gating affected mainly by Ca(2+) and fast gating affected by voltage. Millimolar Ca(2+) increases MthK open probability over 100-fold by mainly increasing the frequency of channel opening while leaving the opening durations unchanged. The Ca(2+) dose-response curve displays an unusually high Hill coefficient (n = approximately 8), suggesting strong coupling between Ca(2+) binding and channel opening. Depolarization affects both the fast gate by dramatically reducing the fast flickers, and to a lesser extent, the slow gate, by increasing MthK open probability. We were able to capture the mechanistic features of MthK with a modified MWC model.

DOI10.1085/jgp.200609534
Alternate JournalJ. Gen. Physiol.
PubMed ID16735753
PubMed Central IDPMC2151542