Persistent activation of min K channels by chemical cross-linking.
Expression of the structurally and functionally distinct min K channel in Xenopus oocytes results in voltage-dependent potassium currents that activate with a characteristic slow time course. Application of a membrane-impermeable chemical cross-linking agent to oocytes expressing min K decreased the time-dependent current, increased its rate of activation, and induced persistently activated inward and outward potassium currents. These effects required membrane depolarization, demonstrating use dependence. Persistently activated channels retained potassium selectivity and sensitivity to block by clofilium and barium. These results suggest that a major conformational change occurs during min K channel gating, which can be stabilized by chemical cross-linking, and are consistent with a model in which min K channels activate by voltage-dependent subunit aggregation.
Vollum Institute, Oregon Health Sciences University, Portland 97201.
M D
MD
Varnum
J
J
Maylie
A
A
Busch
J P
JP
Adelman
D000818:Animals; D001464:Barium / Q000494:pharmacology; D003432:Cross-Linking Reagents / Q000494:pharmacology; D015640:Ion Channel Gating; D046911:Macromolecular Substances; D008564:Membrane Potentials / Q000187:drug effects; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000502:physiology; D015221:Potassium Channels / Q000096:biosynthesis / Q000502:physiology*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D013388:Succinimides / Q000494:pharmacology*; D014982:Xenopus laevis
D003432:Cross-Linking Reagents; D046911:Macromolecular Substances; D015221:Potassium Channels; D000644:Quaternary Ammonium Compounds; D012333:RNA, Messenger; D011994:Recombinant Proteins; D013388:Succinimides; D001464:Barium; C035759:3,3'-dithiobis(sulfosuccinimidyl propionate); C022799:clofilium