Open and Closed Case

Science Signaling  06 Apr 2010:
Vol. 3, Issue 116, pp. ec105
DOI: 10.1126/scisignal.3116ec105

Voltage-dependent ion channels are gated by voltage sensors that show a switchlike response to voltage differences across the membrane. Tao et al. used mutagenesis, electrophysiology, and x-ray crystallography to gain insight into the molecular basis of this response in voltage-dependent potassium channels. An occluded site was identified that catalyzes translation of positive charges across the membrane. The closed channel appears to be associated with a distribution of conformations, depending on the degree of hyperpolarization of the membrane, whereas the open channel appears to be associated with a specific conformation. Thus, the transition of the ion channel from open to closed occurs over a very small voltage difference.

X. Tao, A. Lee, W. Limapichat, D. A. Dougherty, R. MacKinnon, A gating charge transfer center in voltage sensors. Science 328, 67–73 (2010). [Abstract] [Full Text]