The voltage-dependent gate in MthK potassium channels is located at the selectivity filter Academic Article uri icon


MeSH Major

  • Ion Channel Gating
  • Methanobacterium
  • Models, Molecular
  • Potassium Channels, Voltage-Gated
  • Protein Conformation


  • Understanding how ion channels open and close their pores is crucial for comprehending their physiological roles. We used intracellular quaternary ammonium blockers, electrophysiology and X-ray crystallography to locate the voltage-dependent gate in MthK potassium channels from Methanobacterium thermoautotrophicum. Blockers bind in an aqueous cavity between two putative gates: an intracellular gate and the selectivity filter. Thus, these blockers directly probe gate location--an intracellular gate will prevent binding when closed, whereas a selectivity filter gate will always allow binding. Kinetic analysis of tetrabutylammonium block of single MthK channels combined with X-ray crystallographic analysis of the pore with tetrabutyl antimony unequivocally determined that the voltage-dependent gate, like the C-type inactivation gate in eukaryotic channels, is located at the selectivity filter. State-dependent binding kinetics suggest that MthK inactivation leads to conformational changes within the cavity and intracellular pore entrance.

publication date

  • February 2013



  • Academic Article



  • eng

PubMed Central ID

  • PMC3565016

Digital Object Identifier (DOI)

  • 10.1038/nsmb.2473

PubMed ID

  • 23262489

Additional Document Info

start page

  • 159

end page

  • 66


  • 20


  • 2