title: The orientation and molecular movement of a k(+) channel voltage-sensing domain.
abstract: Voltage-gated channels operate through the action of a voltage-sensing domain (membrane segments S1-S4) that controls the conformation of gates located in the pore domain (membrane segments S5-S6). Recent structural studies on the bacterial K(v)AP potassium channel have led to a new model of voltage sensing in which S4 lies in the lipid at the channel periphery and moves through the membrane as a unit with a portion of S3. Here we describe accessibility probing and disulfide scanning experiments aimed at determining how well the K(v)AP model describes the Drosophila Shaker potassium channel. We find that the S1-S3 helices have one end that is externally exposed, S3 does not undergo a transmembrane motion, and S4 lies in close apposition to the pore domain in the resting and activated state.
authors.affiliation: Department of Molecular and Cell Biology, 271 LSA, MC#3200, University of California, Berkeley, CA 94720, USA.
authors.forename: Chris S
authors.initials: CS
authors.lastname: Gandhi
authors.forename: Eliana
authors.initials: E
authors.lastname: Clark
authors.forename: Eli
authors.initials: E
authors.lastname: Loots
authors.forename: Arnd
authors.initials: A
authors.lastname: Pralle
authors.forename: Ehud Y
authors.initials: EY
authors.lastname: Isacoff
mesh_terms: D000818:Animals; D003545:Cysteine / Q000235:genetics; D004229:Dithiothreitol / Q000494:pharmacology; D004330:Drosophila; D029721:Drosophila Proteins; D004553:Electric Conductivity; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007202:Indicators and Reagents / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D008698:Mesylates / Q000378:metabolism; D008954:Models, Biological; D008967:Molecular Biology / Q000379:methods; D009154:Mutation; D009865:Oocytes; D016877:Oxidants / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000737:chemistry* / Q000502:physiology; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry* / Q000502:physiology; D011487:Protein Conformation; D017434:Protein Structure, Tertiary / Q000502:physiology*; D012235:Rhodamines / Q000378:metabolism; D016415:Sequence Alignment; D051637:Shaker Superfamily of Potassium Channels; D013329:Structure-Activity Relationship; D013997:Time Factors; D014982:Xenopus laevis
chemical_list: D029721:Drosophila Proteins; D007202:Indicators and Reagents; D008698:Mesylates; D016877:Oxidants; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D012235:Rhodamines; C496929:Sh protein, Drosophila; D051637:Shaker Superfamily of Potassium Channels; C401833:tetramethylrhodamine methyl ester; C109154:(2-(trimethylammonium)ethyl)methanethiosulfonate; D006861:Hydrogen Peroxide; D003545:Cysteine; D004229:Dithiothreitol