The voltage sensor of the Shaker potassium channel is comprised mostly of positively charged residues in the putative fourth transmembrane segment, S4 (Aggarwal, S.K., and R. MacKinnon. 1996. Neuron. 16:1169-1177; Seoh, S.-A., D. Sigg, D.M. Papazian, and F. Bezanilla. 1996. Neuron. 16:1159-1167). Movement of the voltage sensor in response to a change in the membrane potential was examined indir...

The voltage-sensing phosphatase (VSP) is the first example of an enzyme controlled by changes in membrane potential. VSP has four distinct regions: the transmembrane voltage-sensing domain (VSD), the inter-domain linker, the cytosolic catalytic domain, and the C2 domain. The VSD transmits the changes in membrane potential through the inter-domain linker activating the catalytic domain which the...

Kv11.1 channels are critical for the maintenance of a normal heart rhythm. The flow of potassium ions through these channels is controlled by two voltage-regulated gates, termed "activation" and "inactivation," located at opposite ends of the pore. Crucially in Kv11.1 channels, inactivation gating occurs much more rapidly, and over a distinct range of voltages, compared with activation gating. ...

The structure of the voltage sensor and the detailed physical basis of voltage-dependent activation in ion channels have not been determined. We now have identified conserved molecular rearrangements underlying two major voltage-dependent conformational changes during activation of divergent K(+) channels, ether-à-go-go (eag) and Shaker. Two conserved arginines of the S4 voltage sensor move seq...

Voltage-gated ion channels generate electrical signals in species from bacteria to man. Their voltage-sensing modules are responsible for initiation of action potentials and graded membrane potential changes in response to synaptic input and other physiological stimuli. Extensive structure-function studies, structure determination, and molecular modeling are now converging on a sliding-helix me...

The transmembrane motor protein prestin is thought to underlie outer hair cell (OHC) motility. Prestin expressed in nonauditory cells confers OHC-like electrical characteristics to the cell membrane, including the generation of gating-like currents (or non-linear capacitance), whose voltage dependence is susceptible to membrane tension and initial voltage conditions. Here we report that prestin...

Na+ efflux across basolateral membranes of isolated epithelia of frog skin was tested for voltage sensitivity. The intracellular Na+ transport pool was loaded with 24Na from the apical solution and the rate of isotope appearance in the basolateral solution (JNa23) was measured at timed intervals of 30 s. Basolateral membrane voltage was depolarized by either 50 mM K+, 5 mM Ba++, or 80 mM NH+4. ...

Biological ion channels are molecular devices that allow a rapid flow of ions across the cell membrane. Normal physiological functions, such as generating action potentials for cell-to-cell communication, are highly dependent on ion channels that can open and close in response to external stimuli for regulating ion permeation. Mimicking these biological functions using synthetic structures is a...