Double gaps along Shaker S4 demonstrate omega currents at three different closed states.

The aim of the present study was to investigate in detail how the voltage sensor in the Shaker potassium channel moves during the gating process. After the publication of the open channel structure from the crystallized K(V)AP channel in 2003, an alternative so-called "paddle" model was put forward in contrast to the existing helical screw model. The voltage sensor S4 contains 4 arginine residues relevant for gating, R1(362), R2(365), R3(368) and R4(371), each separated by 2 neutral residues.

More gating charges are needed to open a Shaker K+ channel than are needed to open an rBIIA Na+ channel.

This study presents what is, to our knowledge, a novel technique by means of which the ratio of the single gating charges of voltage-gated rat brain IIA (rBIIA) sodium and Shaker potassium ion channels was estimated. In the experiment, multiple tandems of enhanced green fluorescent protein were constructed and inserted into the C-terminals of Na(+) and K(+) ion channels. cRNA of Na(+) and K(+) ion channels was injected and expressed in Xenopus laevis oocytes.

Molecular cloning and functional characterization of a unique mammalian cardiac Na(v) channel isoform with low sensitivity to the synthetic inactivation inhibitor (-)-(S)-6-amino-alpha-[(4-diphenylmethyl-1-piperazinyl)-methyl]-9H-purine-9-ethanol (SDZ 211-939).

Cardiac voltage-dependent sodium channels (Na(v)) are drug targets for synthetic inactivation inhibitors typified by (+/-)-4- [3-(4-diphenylmethyl-1-piperazinyl)-2-hydroxy propoxy]-1H-indole-2-carbonitrile (DPI 201-106), of which the molecular mode of action is not yet defined. The previous observation by Mevissen and coworkers in 2001 of the electrophysiological ineffectiveness of DPI 201-106 in the bovine heart, in contrast to other species, offers the opportunity for investigating these open questions. We now report about the molecular cloning, expression in Xenopus laevis oocytes, and electrophysiological characterization of a unique bovine heart sodium channel.