Transmembrane movement of the shaker K+ channel S4

Neuron. 1996 Feb;16(2):387-97. doi: 10.1016/s0896-6273(00)80056-2.


We have probed internal and external accessibility of S4 residues to the membrane-impermeant thiol reagent methanethiosulfonate-ethyltrimethlammonium (MTSET) in both open and closed, cysteine-substituted Shaker K+ channels. Our results indicate that S4 traverses the membrane with no more than 5 amino acids in the closed state, and that the distribution of buried residues changes when channels open. This change argues for a displacement of S4 through the plane of the membrane in which an initially intracellular residue moves to within 3 amino acids of the extracellular solution. These results demonstrate that the putative voltage-sensing charges of S4 actually reside in the membrane and that they move outward when channels open. We consider constraints placed on channel structure by these results.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Membrane / metabolism
  • Drosophila / genetics*
  • Mutation*
  • Oocytes / metabolism
  • Patch-Clamp Techniques
  • Potassium Channels / drug effects
  • Potassium Channels / genetics*
  • Potassium Channels / physiology*
  • Sulfhydryl Reagents / pharmacology
  • Xenopus laevis


  • Potassium Channels
  • Sulfhydryl Reagents