Format

Send to:

Choose Destination
See comment in PubMed Commons below
Biophys J. 2010 May 19;98(10):2189-98. doi: 10.1016/j.bpj.2010.02.056.

Calculation of the gating charge for the Kv1.2 voltage-activated potassium channel.

Author information

  • 1Department of Physics, University of Illinois at Urbana-Champaign, Champaign, Illinois, USA.

Abstract

The atomic models of the Kv1.2 potassium channel in the active and resting state, originally presented elsewhere, are here refined using molecular dynamics simulations in an explicit membrane-solvent environment. With a minor adjustment of the orientation of the first arginine along the S4 segment, the total gating charge of the channel determined from >0.5 mus of molecular dynamics simulation is approximately 12-12.7 e, in good accord with experimental estimates for the Shaker potassium channel, indicating that the final models offer a realistic depiction of voltage-gating. In the resting state of Kv1.2, the S4 segment in the voltage-sensing domain (VSD) spontaneously converts into a 3(10) helix over a stretch of 10 residues. The 3(10) helical conformation orients the gating arginines on S4 toward a water-filled crevice within the VSD and allows salt-bridge interactions with negatively charged residues along S2 and S3. Free energy calculations of the fractional transmembrane potential, acting upon key charged residues of the VSD, reveals that the applied field varies rapidly over a narrow region of 10-15 A corresponding to the outer leaflet of the bilayer. The focused field allows the transfer of a large gating charge without translocation of S4 across the membrane.

Copyright 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

PMID:
20483327
[PubMed - indexed for MEDLINE]
PMCID:
PMC2872222
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science Icon for PubMed Central
    Loading ...
    Write to the Help Desk