Portal de Periódicos da CAPES

Voltage-dependent gating of an asymmetric gramicidin channel.

1995; National Academy of Sciences; Volume: 92; Issue: 6 Linguagem: Inglês

10.1073/pnas.92.6.2121

1091-6490

Shigetoshi Oiki, Roger E. Koeppe, Olaf S. Andersen,

Plant and Biological Electrophysiology Studies

In an effort to understand the molecular mechanisms of voltage activation of ion channels, we have chosen a system of known structure and examined the properties of heterodimeric channels formed between [Val1]gramicidin A ([Val1]gA) and [F6Val1]gramicidin A ([F6Val1]gA). Gramicidin channels are usually not voltage-dependent; but the introduction of a single symmetry-breaking dipolar F6Val1 residue into a ([Val1]gA)2 dimer to form the [F6Val1]gA/[Val1]gA heterodimer induces voltage-dependent transitions between two conducting states: a high-conductance state and a zero conductance (closed) state. The distribution between these states varies as a function of the applied potential but is not dependent on the nature of the permeant ion (H+ or Cs+). The permeating ions do not seem to contribute to the apparent gating charge.