The structural homology model of the fourth transmembrane segment (S4 voltage sensor domain), showing the relative position of the T428I mutation was created using the published crystal structure of the related Kv1.2/KCNA2 (potassium voltage-gated channel subfamily A member 2) channel as a template.
In dysfunctional viable segments, unipolar voltage was significantly higher in reversible than in fixed segments (p <0.001), and a unipolar voltage of ≥8.5 mV had optimal power for identifying reversibility on dipyridamole SPECT imaging.
This paper presents a single-ended traveling wave-based fault location method for segmented high voltage DC (HVDC) transmission lines; an overhead line combined with an underground cable.
The majority of causative SCN4A mutations are missense, gain of function mutations (Tsujino et al., 2003; Jurkat-Rott et al., 2010; Lossin et al., 2012), and are usually located within the pore forming segments S5 S6, the voltage sensor segment S4 or the S4 S5 linker of the Nav1.4 channel.
The majority of dominant SCN4A causative mutations in periodic paralysis with myotonia have been found in the pore forming segments S5 S6 or the voltage sensor segment S4 of Nav1.4.
Much data, including crystallographic, support structural models of sodium and potassium channels consisting of S1 S4 transmembrane segments (the "voltage-sensing domain") clustered around a central pore-forming region (S5 S6 segments and the intervening loop).
This data supports the hypothesis that KCNE1 directly interacts with the S4 segment to regulate voltage sensing function.
The R335H mutation, which corresponds to the adult-onset mutation R420H in human Kv3.3, substitutes a histidine residue for the third arginine in the S4 transmembrane segment in the voltage sensor domain (Mock et al., 2010; Waters et al., 2006).
A mutant of the rat Kv1.2 channel in which the helix-turn-helix segment termed the voltage sensor paddle was replaced by the corresponding segment from Kv2.1, known as the paddle chimera Kv channel, was expressed and purified as described previously (Long et al., 2007; Tao and MacKinnon, 2008), with minor modifications.
The first four transmembrane segments form the voltage sensor (S1 S4) while the fifth and sixth transmembrane segments (S5, S6) form the pore domain.
For example, the Arg-rich helical S4 segment of the voltage-gated potassium channel KvAP is proposed to move across the membrane as the channel opens and closes in response to changes in the membrane electric field [42].
