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Nat Struct Mol Biol. 2016 Jan;23(1):31-36. doi: 10.1038/nsmb.3138. Epub 2015 Dec 7.

Structural dynamics of potassium-channel gating revealed by single-molecule FRET.

Author information

Center for Investigation of Membrane Excitability Diseases, Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis MO.
Department of Physics and the Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL.
Howard Hughes Medical Institute, Baltimore, MD.
Department of Biophysics and Biophysical Chemistry, Department of Biophysics, Department of Biomedical Engineering, Baltimore, MD.
Contributed equally


Crystallography has provided invaluable insights regarding ion-channel selectivity and gating, but to advance understanding to a new level, dynamic views of channel structures within membranes are essential. We labeled tetrameric KirBac1.1 potassium channels with single donor and acceptor fluorophores at different sites and then examined structural dynamics within lipid membranes by single-molecule fluorescence resonance energy transfer (FRET). We found that the extracellular region is structurally rigid in both closed and open states, whereas the N-terminal slide helix undergoes marked conformational fluctuations. The cytoplasmic C-terminal domain fluctuates between two major structural states, both of which become less dynamic and move away from the pore axis and away from the membrane in closed channels. Our results reveal mobile and rigid conformations of functionally relevant KirBac1.1 channel motifs, implying similar dynamics for similar motifs in eukaryotic Kir channels and in cation channels in general.

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