Electron microscopic analysis of KvAP voltage-dependent K+ channels in an open conformation

Nature. 2004 Aug 12;430(7001):806-10. doi: 10.1038/nature02735.


Voltage-dependent ion channels serve as field-effect transistors by opening a gate in response to membrane voltage changes. The gate's response to voltage is mediated by voltage sensors, which are arginine-containing structures that must move with respect to the membrane electric field. We have analysed by electron microscopy a voltage-dependent K(+) channel from Aeropyrum pernix (KvAP). Fab fragments were attached to 'voltage sensor paddles' and identified in the electron microscopy map at 10.5 A resolution. The extracellular surface location of the Fab fragments in the map is consistent with the membrane-depolarized, open conformation of the channel in electrophysiological experiments. Comparison of the map with a crystal structure demonstrates that the voltage sensor paddles are 'up' (that is, near the channel's extracellular surface) and situated at the protein-lipid interface. This finding supports the hypothesis that in response to changes in voltage the sensors move at the protein-lipid interface rather than in a gating pore surrounded by protein.

Publication types

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

MeSH terms

  • Aeropyrum / chemistry*
  • Amino Acid Sequence
  • Cryoelectron Microscopy*
  • Crystallography, X-Ray
  • Immunoglobulin Fab Fragments / chemistry
  • Immunoglobulin Fab Fragments / immunology
  • Molecular Sequence Data
  • Potassium Channels, Voltage-Gated / chemistry*
  • Potassium Channels, Voltage-Gated / immunology
  • Potassium Channels, Voltage-Gated / metabolism
  • Potassium Channels, Voltage-Gated / ultrastructure*
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Structure-Activity Relationship


  • Immunoglobulin Fab Fragments
  • Potassium Channels, Voltage-Gated

Associated data

  • PDB/1ORQ
  • PDB/1ORS