Download MendeleyThe voltage-dependent gate in MthK potassium channels is located at the selectivity filter.
Posson, D.J., McCoy, J.G., Nimigean, C.M.(2013) Nat Struct Mol Biol 20: 159-166
- PubMed: 23262489
- DOI: https://doi.org/10.1038/nsmb.2473
- Primary Citation of Related Structures:
4HYO, 4HZ3 - PubMed Abstract:
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.
Organizational Affiliation:
Department of Anesthesiology, Weill Cornell Medical College, New York, New York, USA. djp2003@med.cornell.edu
