Evidence that the S6 segment of the Shaker voltage-gated K+ channel comprises part of the pore

Nature. 1994 Jan 13;367(6459):179-82. doi: 10.1038/367179a0.


Potassium channels are highly selective and allow the rapid flux of potassium ions through their pore. Several studies have implicated the H5 (P or SS1-SS2) segment as part of the pore in voltage-gated ion channels. The proposal that H5 spans at least 80% of the electric potential drop across the K+ channel pore is based on altered internal tetraethylammonium sensitivity arising from mutations of H5 residues that are 100% conserved among K+ channels having differing sensitivity to tetraethylammonium. Here we report that the S6 segment is also involved in K+ ion permeation and in governing the sensitivity to internal tetraethylammonium and barium. Transplanting the S6 segment of NGK2 into Shaker causes this S6 chimaera to adopt the single-channel conductance and sensitivity to internal tetraethylammonium and barium ions from the NGK2 channel. The differences between NGK2 and Shaker in external tetraethylammonium sensitivity, but not single-channel conductance, can be attributed to the differences in their H5 sequences. Three nonconserved S6 residues have been found to affect either single-channel conductance or internal tetraethylammonium sensitivity.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Barium / pharmacology
  • Female
  • Ion Channel Gating
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Oocytes / physiology
  • Peptide Fragments / physiology
  • Peptides / physiology
  • Potassium Channels / chemistry
  • Potassium Channels / drug effects
  • Potassium Channels / physiology*
  • Recombinant Fusion Proteins
  • Shaker Superfamily of Potassium Channels
  • Tetraethylammonium
  • Tetraethylammonium Compounds / pharmacology
  • Xenopus


  • Peptide Fragments
  • Peptides
  • Potassium Channels
  • Recombinant Fusion Proteins
  • Shaker B potassium channel polypeptide
  • Shaker Superfamily of Potassium Channels
  • Tetraethylammonium Compounds
  • Barium
  • Tetraethylammonium