[PDF][PDF] Voltage sensors in domains III and IV, but not I and II, are immobilized by Na+ channel fast inactivation

A Cha, PC Ruben, AL George, E Fujimoto, F Bezanilla - Neuron, 1999 - cell.com
A Cha, PC Ruben, AL George, E Fujimoto, F Bezanilla
Neuron, 1999cell.com
Using site-directed fluorescent labeling, we examined conformational changes in the S4
segment of each domain of the human skeletal muscle sodium channel (hSkM1). The
fluorescence signals from S4 segments in domains I and II follow activation and are
unaffected as fast inactivation settles. In contrast, the fluorescence signals from S4 segments
in domains III and IV show kinetic components during activation and deactivation that
correlate with fast inactivation and charge immobilization. These results indicate that in …
Abstract
Using site-directed fluorescent labeling, we examined conformational changes in the S4 segment of each domain of the human skeletal muscle sodium channel (hSkM1). The fluorescence signals from S4 segments in domains I and II follow activation and are unaffected as fast inactivation settles. In contrast, the fluorescence signals from S4 segments in domains III and IV show kinetic components during activation and deactivation that correlate with fast inactivation and charge immobilization. These results indicate that in hSkM1, the S4 segments in domains III and IV are responsible for voltage-sensitive conformational changes linked to fast inactivation and are immobilized by fast inactivation, while the S4 segments in domains I and II are unaffected by fast inactivation.
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