Direct physical measure of conformational rearrangement underlying potassium channel gating.
In response to membrane depolarization, voltage-gated ion channels undergo a structural rearrangement that moves charges or dipoles in the membrane electric field and opens the channel-conducting pathway. By combination of site-specific fluorescent labeling of the Shaker potassium channel protein with voltage clamping, this gating conformational change was measured in real time. During channel activation, a stretch of at least seven amino acids of the putative transmembrane segment S4 moved from a buried position into the extracellular environment. This movement correlated with the displacement of the gating charge, providing physical evidence in support of the hypothesis that S4 is the voltage sensor of voltage-gated ion channels.
Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA.
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Mannuzzu
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Moronne
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Isacoff
D000595:Amino Acid Sequence; D000818:Animals; D004396:Coloring Agents; D005453:Fluorescence; D005456:Fluorescent Dyes; D015640:Ion Channel Gating; D008564:Membrane Potentials; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009865:Oocytes; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments; D015221:Potassium Channels / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D012235:Rhodamines; D014981:Xenopus
D004396:Coloring Agents; D005456:Fluorescent Dyes; D010446:Peptide Fragments; D015221:Potassium Channels; D012235:Rhodamines; C088750:S4 peptide, Drosophila Shaker potassium channel; C005358:tetramethylrhodamine