Gating charge immobilization caused by the transition between inactivated states in the Kv1.5 channel

Biophysical Journal
Z Wang, D Fedida

Abstract

Sustained Na(+) or Li(+) conductance is a feature of the inactivated state in wild-type (WT) and nonconducting Shaker and Kv1.5 channels, and has been used here to investigate the cause of off-gating charge immobilization in WT and Kv1.5-W472F nonconducting mutant channels. Off-gating immobilization in response to brief pulses in cells perfused with NMG/NMG is the result of a more negative voltage dependence of charge recovery (V(1/2) is -96 mV) compared with on-gating charge movement (V(1/2) is -6.3 mV). This shift is known to be associated with slow inactivation in Shaker channels and the disparity is reduced by 40 mV, or approximately 50% in the presence of 135 mM Cs. Off-gating charge immobilization is voltage-dependent with a V(1/2) of -12 mV, and correlates well with the development of Na(+) conductance on repolarization through C-type inactivated channels (V(1/2) is -11 mV). As well, the time-dependent development of the inward Na(+) tail current and gating charge immobilization after depolarizing pulses of different durations has the same time constant (tau = 2.7 ms). These results indicate that in Kv1.5 channels the transition to a stable C-type inactivated state takes only 2-3 ms and results in strong charge immobiliz...Continue Reading

References

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Citations

Feb 26, 2003·The Journal of General Physiology·Shetuan ZhangDavid Fedida
Jun 14, 2006·The Journal of General Physiology·Hongying Gang, Shetuan Zhang
Oct 18, 2006·The Journal of General Physiology·Gyorgy Panyi, Carol Deutsch
Apr 1, 2009·The Journal of General Physiology·Zhuren WangDavid Fedida
Jun 24, 2008·Biophysical Journal·Gianina PanaghieGeoffrey W Abbott
Jul 16, 2005·The Journal of Physiology·Harley T KurataDavid Fedida
Dec 1, 2005·Progress in Biophysics and Molecular Biology·Harley T Kurata, David Fedida

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