Referenced in: none

Automatically associated channels: Kv10.1

Title: Calibrated measurement of gating-charge arginine displacement in the KvAP voltage-dependent K+ channel.

Authors: Vanessa Ruta, Jiayun Chen, Roderick MacKinnon

Journal, date & volume: Cell, 2005 Nov 4 , 123, 463-75

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/16269337

Abstract
Voltage-dependent ion channels open and conduct ions in response to changes in cell-membrane voltage. The voltage sensitivity of these channels arises from the motion of charged arginine residues located on the S4 helices of the channel's voltage sensors. In KvAP, a prokaryotic voltage-dependent K+ channel, the S4 helix forms part of a helical hairpin structure, the voltage-sensor paddle. We have measured the membrane depth of residues throughout the KvAP channel using avidin accessibility to different-length tethered biotin reagents. From these measurements, we have calibrated the tether lengths and derived the thickness of the membrane that forms a barrier to avidin penetration, allowing us to determine the magnitude of displacement of the voltage-sensor paddles during channel gating. Here we show that the voltage-sensor paddles are highly mobile compared to other regions of the channel and transfer the gating-charge arginines 15-20 A through the membrane to open the pore.