We examined voltage-dependent conformational changes in three specific regions of the Shaker potassium channel with site-directed fluorescent labeling: the fourth transmembrane segment (S4), the second transmembrane segment (S2), and the putative pore region. The fluorescence changes displayed distinctive properties that correlate with gating, activation, and slow inactivation of the channel. T...

The resistance in series with the membrane capacitance in the giant axon of the squid Loligo pealei was measured using potentiometric probes that exhibit absorbance changes proportional to the voltage across the plasma membrane proper. The method relies upon the fact that a voltage drop across the series resistance produces a deviation in the true transmembrane voltage from that imposed by a vo...

The paper describes a general method for analysis of time courses of transmembrane voltage induced by time-varying electric fields. Using this method, a response to a wide variety of time-varying fields can be studied. We apply it to different field shapes used for Ž . electroporation and electrofusion: rectangular pulses, trapezoidal pulses approximating rectangular pulses with finite rise tim...

We model the dynamics of voltage-driven transport of DNA hairpins through transmembrane channels. A two-dimensional stochastic model of the DNA translocation process is fit to the measurements of Mathé, who pulled self-hybridized DNA hairpins through lipid-embedded alpha-hemolysin channels. As the channel was too narrow to accommodate hybridized DNA, dehybridization of the hairpin became the ra...

Electropermeabilization and cell death caused by the exposure to high voltage electric pulses depends on the parameters of pulses, as well as the composition of the extracellular medium. We studied the influence of extracellular conductivity on electropermeabilization and survival of cells in vitro. For this purpose, we used a physiological medium with a conductivity of 1.6 S/m and three artifi...

Many common medications block delayed rectifier K(+) channels and prolong the duration of cardiac action potentials. Here we investigate the molecular mechanisms of voltage-dependent block of human ether-a-go-go-related gene (HERG) delayed rectifier K(+) channels expressed in Xenopus laevis oocytes by quinidine, an antiarrhythmic drug, and vesnarinone, a cardiotonic drug. The IC(50) values dete...

Voltage dependence of fusion induced by class II and class III viral fusion proteins was investigated. Class II proteins from Ross River and Sindbus virus and a mutant class III protein from Epstein Barr virus were found to induce cell-cell fusion that is voltage dependent. Combined with previous studies, in all, four class II and two class III protein have now been shown to exhibit voltage-dep...

Dipeptidyl aminopeptidase-like proteins (DPLPs) interact with Kv4 channels and thereby induce a profound remodeling of activation and inactivation gating. DPLPs are constitutive components of the neuronal Kv4 channel complex, and recent observations have suggested the critical functional role of the single transmembrane segment of these proteins (Zagha, E., A. Ozaita, S.Y. Chang, M.S. Nadal, U....

Voltage-gated potassium (Kv) channels are tetramers, each subunit presenting six transmembrane segments (S1-S6), with each S1-S4 segments forming a voltage-sensing domain (VSD) and the four S5-S6 forming both the conduction pathway and its gate. S4 segments control the opening of the intracellular activation gate in response to changes in membrane potential. Crystal structures of several voltag...