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XB-ART-43489
J Biol Chem 2011 May 06;28618:16414-25. doi: 10.1074/jbc.M110.198010.
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Uncoupling charge movement from channel opening in voltage-gated potassium channels by ruthenium complexes.

Jara-Oseguera A , Ishida IG , Rangel-Yescas GE , Espinosa-Jalapa N , Pérez-Guzmán JA , Elías-Viñas D , Le Lagadec R , Rosenbaum T , Islas LD .


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The Kv2.1 channel generates a delayed-rectifier current in neurons and is responsible for modulation of neuronal spike frequency and membrane repolarization in pancreatic β-cells and cardiomyocytes. As with other tetrameric voltage-activated K(+)-channels, it has been proposed that each of the four Kv2.1 voltage-sensing domains activates independently upon depolarization, leading to a final concerted transition that causes channel opening. The mechanism by which voltage-sensor activation is coupled to the gating of the pore is still not understood. Here we show that the carbon-monoxide releasing molecule 2 (CORM-2) is an allosteric inhibitor of the Kv2.1 channel and that its inhibitory properties derive from the CORM-2 ability to largely reduce the voltage dependence of the opening transition, uncoupling voltage-sensor activation from the concerted opening transition. We additionally demonstrate that CORM-2 modulates Shaker K(+)-channels in a similar manner. Our data suggest that the mechanism of inhibition by CORM-2 may be common to voltage-activated channels and that this compound should be a useful tool for understanding the mechanisms of electromechanical coupling.

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Species referenced: Xenopus laevis

References [+] :
Aggarwal, Contribution of the S4 segment to gating charge in the Shaker K+ channel. 1996, Pubmed, Xenbase