Cross talk between activation and slow inactivation gates of Shaker potassium channels.
This study addresses the energetic coupling between the activation and slow inactivation gates of Shaker potassium channels. To track the status of the activation gate in inactivated channels that are nonconducting, we used two functional assays: the accessibility of a cysteine residue engineered into the protein lining the pore cavity (V474C) and the liberation by depolarization of a Cs(+) ion trapped behind the closed activation gate. We determined that the rate of activation gate movement depends on the state of the inactivation gate. A closed inactivation gate favors faster opening and slower closing of the activation gate. We also show that hyperpolarization closes the activation gate long before a channel recovers from inactivation. Because activation and slow inactivation are ubiquitous gating processes in potassium channels, the cross talk between them is likely to be a fundamental factor in controlling ion flux across membranes.
Panyi
Gyorgy
G
Department of Biophysics and Cell Biology, University of Debrecen, 4032 Debrecen, Hungary.
Deutsch
Carol
C
D002478:Cells, Cultured; D002586:Cesium / Q000502:physiology; D003545:Cysteine / Q000502:physiology; D004594:Electrophysiology; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*; D007668:Kidney / Q000166:cytology / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology; D009154:Mutation / Q000235:genetics; D020239:Receptor Cross-Talk / Q000502:physiology*; D051637:Shaker Superfamily of Potassium Channels / Q000235:genetics / Q000502:physiology*; D013997:Time Factors
D051637:Shaker Superfamily of Potassium Channels; D002586:Cesium; D003545:Cysteine