Interactions between a Pore-Blocking Peptide and the Voltage Sensor of the Sodium Channel: An Electrostatic Approach to Channel Geometry

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• 作者：Robert J. French ; Elzbieta Prusak-Sochaczewski ; Gerald W. Zamponi ; Stefan Becker ; A. Shavantha Kularatna ; Richard Horn
• 刊名：Neuron
• 出版年：1996
• 出版时间：February 1996
• 年：1996
• 卷：16
• 期：2
• 页码：407-413
• 全文大小：132 K

文摘

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 μ-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 inhibits 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.