Spectroscopic mapping of voltage sensor movement in the Shaker potassium channel

Voltage-gated ion channels underlie the generation of action potentials and trigger neurosecretion and muscle contraction. These channels consist of an inner pore-forming domain, which contains the ion permeation pathway and elements of its gates, together with four voltage-sensing domains, which re...

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Bibliographic Details
Published in:Nature (London) 1999-12, Vol.402 (6763), p.813-817
Main Authors: Glauner, K. S., Mannuzzu, L. M., Gandhi, C. S., Isacoff, E. Y.
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Cell membranes. Ionic channels. Membrane pores
Cell structures and functions
Electrochemistry
Energy transfer
Fluorescence
Fundamental and applied biological sciences. Psychology
Humanities and Social Sciences
Ion Channel Gating
letter
Molecular and cellular biology
multidisciplinary
Mutagenesis, Site-Directed
Physics
Potassium Channels - chemistry
Potassium Channels - genetics
Potassium Channels - metabolism
Protein Conformation
Resonance
Science
Science (multidisciplinary)
Shaker Superfamily of Potassium Channels
Spectrometry, Fluorescence - methods
Spectrum analysis
Xenopus
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Summary:Voltage-gated ion channels underlie the generation of action potentials and trigger neurosecretion and muscle contraction. These channels consist of an inner pore-forming domain, which contains the ion permeation pathway and elements of its gates, together with four voltage-sensing domains, which regulate the gates 1 , 2 , 3 , 4 , 5 , 6 . To understand the mechanism of voltage sensing it is necessary to define the structure and motion of the S4 segment, the portion of each voltage-sensing domain that moves charged residues across the membrane in response to voltage change 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 . We have addressed this problem by using fluorescence resonance energy transfer as a spectroscopic ruler 15 , 16 , 17 to determine distances between S4s in the Shaker K + channel in different gating states. Here we provide evidence consistent with S4 being a tilted helix that twists during activation. We propose that helical twist contributes to the movement of charged side chains across the membrane electric field and that it is involved in coupling voltage sensing to gating.
ISSN:0028-0836
1476-4687
DOI:10.1038/45561