Functional Site-Directed Fluorometry 75
Sesti F, Rajan S, Gonzalez-Colaso R, Nikolaeva N, Goldstein SAN (2003) Hyperpolarization
moves S4 sensors inward to open MVP, a methanococcal voltage-gated potassium channel.
Nat Neurosci 6:353–361
Sheets MF, Kyle JW, Kallen RG, Hanck DA (1999). The Na channel voltage sensor associated
with inactivation is localized to the external charged residues of domain IV, S4. Biophys J
77:747–757
Sheets MF, Kyle JW, Hanck DA (2000) The role of the putative inactivation lid in sodium channel
gating current immobilization. J Gen Physiol 115:609–620
Shi YP, Cheng YM, Slyke ACV, Claydon TW (2014) External protons destabilize the activated
voltage sensor in hERG channels. Eur Biophys J 43:59–69
Slatin SL, Qiu X-Q, Jakes KS, Finkelstein A (1994) Identification of a translocated protein seg-
ment in a voltage-dependent channel. Nature 371:158–161
Smith PL, Yellen G (2002) Fast and slow voltage sensor movements in HERG potassium channels.
J. Gen Physiol 119:275–293
Sonar S, Lee C-P, Coleman M, Patel N, Liu X, Marti T, Khorana HG, RajBhandary UL, Rothschild
KJ (1994) Site-directed isotope labelling and FTIR spectroscopy of bacteriorhodopsin. Nat
Struct Mol Biol 1:512–517
Sørensen JB, Cha A, Latorre R, Rosenman E, Bezanilla F (2000) Deletion of the S3–S4 linker
in the Shaker potassium channel reveals two quenching groups near the outside of S4. J Gen
Physiol 115:209–222
Souvignier G, Gerwert K (1992) Proton uptake mechanism of bacteriorhodopsin as determined by
time-resolved stroboscopic-FTIR-spectroscopy. Biophys J 63:1393–1405
Steinhoff HJ, Mollaaghababa R, Altenbach C, Hideg K, Krebs M, Khorana HG, Hubbell WL
(1994) Time-resolved detection of structural changes during the photocycle of spin-labeled
bacteriorhodopsin. Science 266:105–107
Tan PS, Perry MD, Ng CA, Vandenberg JI, Hill AP (2012) Voltage-sensing domain mode shift is
coupled to the activation gate by the N-terminal tail of hERG channels. J Gen Physiol 140:293–
306
Thouta S, Sokolov S, Abe Y, Clark SJ, Cheng YM, Claydon TW (2014) Proline scan of the hERG
channel S6 helix reveals the location of the intracellular pore gate. Biophys J 106:1057–1069
Timpe LC, Schwarz TL, Tempel BL, Papazian DM, JanYN, Jan LY (1988) Expression of func-
tional potassium channels from Shaker cDNA in Xenopus oocytes. Nature 331:143–145
Tombola F, Pathak MM, Isacoff EY (2005) Voltage-sensing arginines in a potassium channel per-
meate and occlude cation-selective pores. Neuron 45:379–388
Tombola F, Ulbrich MH, Kohout SC, Isacoff EY (2010) The opening of the two pores of the Hv1
voltage-gated proton channel is tuned by cooperativity. Nat Struct Mol Biol 17:44–50
Ulens C, Spurny R, Thompson AJ, Alqazzaz M, Debaveye S, Han L, Price K, Villalgordo JM,
Tresadern G, Lynch JW, Lummis SCR (2014) The prokaryote ligand-gated ion channel ELIC
captured in a pore blocker-bound conformation by the Alzheimer's disease drug memantine.
Structure 22:1399–1407
Unger VM, Schertler GF (1995) Low resolution structure of bovine rhodopsin determined by
electron cryo-microscopy. Biophys J 68:1776–1786
Unwin N (1995) Acetylcholine receptor channel imaged in the open state. Nature 373:37–43
Vaid M, Claydon TW, Rezazadeh S, Fedida D (2008) Voltage clamp fluorimetry reveals a nov-
el outer pore instability in a mammalian voltage-gated potassium channel. J Gen Physiol
132:209–222
Villalba-Galea CA, Sandtner W, Starace DM, Bezanilla F (2008) S4-based voltage sensors have
three major conformations. Proc Natl Acad Sci U S A 105:17600–17607
Villalba-Galea CA, Miceli F, Taglialatela M, Bezanilla F (2009) Coupling between the voltage-
sensing and phosphatase domains of Ci-VSP. J Gen Physiol 134:5–14
Virkki LV, Murer H, Forster IC (2006) Voltage clamp fluorometric measurements on a type II Na+-
coupled Pi cotransporter: shedding light on substrate binding order. J Gen Physiol 127:539–555