Crystal structure and mechanism of a calcium-gated potassium channel

Nature. 2002 May 30;417(6888):515-22. doi: 10.1038/417515a.


Ion channels exhibit two essential biophysical properties; that is, selective ion conduction, and the ability to gate-open in response to an appropriate stimulus. Two general categories of ion channel gating are defined by the initiating stimulus: ligand binding (neurotransmitter- or second-messenger-gated channels) or membrane voltage (voltage-gated channels). Here we present the structural basis of ligand gating in a K(+) channel that opens in response to intracellular Ca(2+). We have cloned, expressed, analysed electrical properties, and determined the crystal structure of a K(+) channel (MthK) from Methanobacterium thermoautotrophicum in the Ca(2+)-bound, opened state. Eight RCK domains (regulators of K(+) conductance) form a gating ring at the intracellular membrane surface. The gating ring uses the free energy of Ca(2+) binding in a simple manner to perform mechanical work to open the pore.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Calcium / pharmacology
  • Crystallography, X-Ray
  • Electrophysiology
  • Ion Channel Gating* / drug effects
  • Ligands
  • Lipid Bilayers / metabolism
  • Methanobacterium / chemistry*
  • Methanobacterium / genetics
  • Models, Molecular
  • Molecular Sequence Data
  • Potassium Channels, Calcium-Activated / chemistry*
  • Potassium Channels, Calcium-Activated / genetics
  • Potassium Channels, Calcium-Activated / metabolism*
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Sequence Alignment
  • Structure-Activity Relationship
  • Thermodynamics


  • Bacterial Proteins
  • Ligands
  • Lipid Bilayers
  • Potassium Channels, Calcium-Activated
  • Calcium

Associated data

  • PDB/1LNQ