The Voltage-Dependent Chloride Channel of Torpedo Electroplax
Our intention in this chapter is to describe the remarkable functional properties—some would say the eccentric behavior—of an anion transport protein found in the electric organ of electric rays, such as Torpedo and Narke. This is a Cl−-specific ion channel, commonly called the “Torpedo Cl− channel.” Like all ion channels, this protein catalyzes the electrodiffusive, thermodynamically downhill flow of ions across the membrane in which it resides, and thus should be classed as a membrane “leak.” Lest this term be considered pejorative by those familiar with active transporters which work to build up transmembrane ion gradients, we should point out that cells have good reasons to maintain specific leaks across their membranes; for instance, a leak for Cl−, in combination with a Cl− concentration gradient, can give rise to a transmembrane voltage, as is, we imagine, the purpose of the Torpedo Cl− channel.
KeywordsElectric Organ Conductance Level Planar Lipid Bilayer Activation Gate Planar Bilayer
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