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Neuron. 1996 Feb;16(2):407-13.

Interactions between a pore-blocking peptide and the voltage sensor of the sodium channel: an electrostatic approach to channel geometry.

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Department of Medical Physiology, Faculty of Medicine, University of Calgary, Alberta, Canada.


Few experimental data illuminate the relationship between the molecular structures that mediate ion conduction through voltage-dependent ion channels and the structures responsible for sensing transmembrane voltage and controlling gating. To fill this void, we have used a strongly cationic, mutated mu-conotoxin peptide, which only partially blocks current through voltage-dependent sodium channels, to study voltage-dependent activation gating in both bound and unbound channels. When the peptide binds to the ion-conducting pore, it inhibit channel opening, necessitating stronger depolarization for channel activation. We show that this activation shift could result entirely from electrostatic inhibition of the movement of the voltage-sensing S4 charges and estimate the approximate physical distance through which the S4 charges move.

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