Cysteine-modifying reagents alter the gating of the rat cloned potassium channel Kv1.4.
The effects of cysteine-modifying reagents on the gating of rat cloned Kv1.4 channels expressed in HEK-293 cells were examined using the whole-cell patch-clamp technique. Cells transfected with Kv1.4 expressed a rapidly inactivating K+ current with a mid-point of activation of -31 mV and a slope factor of 5 mV measured with tail current protocols in 35 mM Rb+ external solutions. The cysteine-specific oxidizing agents 2,2'-dithiobis-5-nitropyridine (DTBNP, 50 microM) and chloramine-T (CL-T, 500 microM) removed inactivation of Kv1.4. These effects were reversed by the reducing agent dithiothreitol (DTT, 10mM). In addition, DTBNP and CL-T also slowed Kv1.4 deactivation and increased the voltage sensitivity of deactivation. The action of cysteine-modifying reagents on Kv1.4 suggests that redox state affects channel gating, with oxidation tending to stabilize the open state of the channel, both by removing inactivation and slowing deactivation.
Stephens
G J
GJ
Electrophysiology Laboratory, Wyeth Research (UK), Huntercombe Lane South, Taplow SL6 OPH, Berkshire, UK.
Owen
D G
DG
Robertson
B
B
D000818:Animals; D002999:Clone Cells; D003545:Cysteine / Q000494:pharmacology*; D004594:Electrophysiology; D005110:Extracellular Space / Q000737:chemistry; D015640:Ion Channel Gating / Q000187:drug effects; D015221:Potassium Channels / Q000502:physiology*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D012413:Rubidium / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology
D015221:Potassium Channels; D011725:Pyridines; D013439:Sulfhydryl Reagents; C011801:2,2'-dithiobis(5-nitropyridine); D003545:Cysteine; D012413:Rubidium