Voltage-Dependent Gating of an Asymmetric Gramicidin Channel
by Oiki, S.; Koeppe, R. E.; Andersen, O. S.
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 [Val(1)]gramicidin A ([Val(1)]gA) and [F(6)Val(1)]gramicidin A ([F(6)Val(1)]gA). Gramicidin channels are usually not voltage-dependent; but the introduction of a single symmetrybreaking dipolar F(6)Val(1) residue into a ([Val(1)]gA)(2) dimer to form the [F(6)Val(1)]gA/[Val(1)]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.
- Journal
- Proceedings of the National Academy of Sciences of the United States of America
- Volume
- 92
- Issue
- 6
- Year
- 1995
- Start Page
- 2121-2125
- URL
- https://dx.doi.org/10.1073/pnas.92.6.2121
- ISBN/ISSN
- 1091-6490; 0027-8424
- DOI
- 10.1073/pnas.92.6.2121