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

被引:151
作者
Posson, DJ
Ge, PH
Miller, C
Bezanilla, F
Selvin, PR
机构
[1] Univ Illinois, Dept Phys, Urbana, IL 61801 USA
[2] Univ Illinois, Ctr Biophys, Urbana, IL 61801 USA
[3] Brandeis Univ, Howard Hughes Med Inst, Dept Biochem, Waltham, MA 02454 USA
[4] Univ Calif Los Angeles, Sch Med, Dept Physiol, Los Angeles, CA 90095 USA
[5] Univ Calif Los Angeles, Sch Med, Dept Anesthesiol, Los Angeles, CA 90095 USA
关键词
D O I
10.1038/nature03819
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Voltage-gated ion channels open and close in response to voltage changes across electrically excitable cell membranes(1). Voltage-gated potassium (Kv) channels are homotetramers with each subunit constructed from six transmembrane segments, S1 - S6 (ref. 2). The voltage-sensing domain ( segments S1 - S4) contains charged arginine residues on S4 that move across the membrane electric field(2,3), modulating channel open probability. Understanding the physical movements of this voltage sensor is of fundamental importance and is the subject of controversy. Recently, the crystal structure of the KvAP(4) channel motivated an unconventional 'paddle model' of S4 charge movement, indicating that the segments S3b and S4 might move as a unit through the lipid bilayer with a large ( 15-20-angstrom) transmembrane displacement(5). Here we show that the voltage-sensor segments do not undergo significant transmembrane translation. We tested the movement of these segments in functional Shaker K 1 channels by using luminescence resonance energy transfer to measure distances between the voltage sensors and a pore-bound scorpion toxin. Our results are consistent with a 2-angstrom vertical displacement of S4, not the large excursion predicted by the paddle model. This small movement supports an alternative model in which the protein shapes the electric field profile, focusing it across a narrow region of S4 ( ref. 6).
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页码:848 / 851
页数:4
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