Atomic scale movement of the voltage-sensing region in a potassium channel measured via spectroscopy

Article Abstract:

It has been possible to measure actual voltage-induced distance changes in an ion channel. It seems that the voltage sensor does not need to undergo a large conformational change. This research involved using lanthanide-based resonance energy transfer to measure distances between Shaker potassium channel subunits at specific residues. Specific sites in the channel were fluorescently labelled by substituting a cysteine for a particular residue and attaching cysteine-reactive compounds or a donor or an acceptor to the same site in the four subunits of the channel.

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A proton pore in a potassium channel voltage sensor reveals a focused electric field

Article Abstract:

Replacing the first S4 (fourth transmembrane segment) arginine by histidine in the Shaker potassium channel creates a proton pore when the cell is hyperpolarized. The conclusion is that, at hyperpolarized potentials, a narrow barrier in the channel protein that focuses the electric field to a small voltage-sensitive region must separate water and protons from the internal and external solutions.

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Small vertical movement of a K(super +) channel voltage sensor measured with luminescence energy transfer

Article Abstract:

Luminescence resonance energy transfer (LRET) is used for measuring the distances between voltage sensor segments in functional Shaker K(super +) channels and a pore-bound scorpion toxin. A 2-A vertical displacement of S4 and no significant transmembrane translation were observed in the voltage-sensor segments.

Membrane proteins, Energy transformation

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