The recently determined structure of a mammalian voltage-gated potassium channel has important implications for our understanding of voltage-sensing and gating mechanisms in channels. It is also the first crystal structure of an overexpressed eukaryotic membrane protein.

The permeability of K channels to various cations is studied in myelinated nerve. Ionic currents under voltage clamp are measured in Ringer solution containing tetrodotoxin and a high concentration of the test ion. Reversal potentials for current in K channels are determined and used with the Goldman-Hodgkin-Katz equation to calculate relative permeabilities. The ratios P(Tl):P(K):P(Rb):P(NHNH4...

This second of three papers, in which we functionally characterize activation gating in Shaker potassium channels, focuses on the properties of a mutant channel (called V2), in which the leucine at position 382 (in the Shaker B sequence) is mutated to valine. The general properties of V2's ionic and gating currents are consistent with changes in late gating transitions, in particular, with V2 d...

We report here several unusual features of inactivation of the rat Kv2.1 delayed rectifier potassium channel, expressed in Xenopus oocytes. The voltage dependence of inactivation was U-shaped, with maximum inactivation near 0 mV. During a maintained depolarization, development of inactivation was slow and only weakly voltage dependent (tau = 4 s at 0 mV; tau = 7 s at +80 mV). However, recovery ...

(Shi et al., 1996, and references therein). In the heart Many types of channels and receptors are expressed and the ear, a single-spanning transmembrane protein, in the nervous system, contributing to the complex and minK, coassembles with KvLQT1 tetramers to form a diverse functional repertoires of neurons. Regulation of delayed rectifier that plays an essential role in repolartranscription an...

Sulfonylurea drugs stimulate endogenous insulin secretion by blockade of ATP-sensitive potassium channels in pancreatic beta cells. These drugs are widely used in the treatment of type 2 diabetes. However, as ATP-sensitive potassium channels also exist in cardiomyocytes and coronary and peripheral arterial vascular smooth muscle cells, sulfonylurea drug usage in theory may cause unwanted cardio...

Human ether-a-go-go-related gene (HERG) potassium channels are one primary target for the pharmacological treatment of cardiac arrhythmias by class III antiarrhythmic drugs. These drugs are characterized by high antiarrhythmic efficacy, but they can also initiate life-threatening "torsade de pointes" tachyarrhythmias. Recently, it has been suggested that combining potassium and calcium channel ...

Voltage gated potassium channels have been extensively studied in relation to cancer. In this review, we will focus on the role of two potassium channels, Ether à-go-go (Eag), Human ether à-go-go related gene (HERG), in cancer and their potential therapeutic utility in the treatment of cancer. Eag and HERG are expressed in cancers of various organs and have been implicated in cell cycle progres...

Since 1995, when a potassium channel gene, hERG (human ether-à-go-go-related gene), now referred to as KCNH2, encoding the rapid component of cardiac delayed rectifier potassium channels was identified as being responsible for type 2 congenital long-QT syndrome, a number of potassium channel genes have been shown to cause different types of inherited cardiac arrhythmia syndromes. These include ...

A new method for simultaneous mapping of cell topography and ion fluxes was developed. A highly sensitive ion sensor system was generated by coating atomic force microscopy tips with a PVC layer containing valinomycin, an ionophore for potassium. The activity of specific ions was traced on artificial ion-releasing PVC substrates. A boundary potential was generated owing to the selective exchang...