Positively charged voltage sensors of sodium and potassium channels are driven outward through the membrane's electric field upon depolarization. This movement is coupled to channel opening. A recent model based on studies of the KvAP channel proposes that the positively charged voltage sensor, christened the “voltage-sensor paddle”, is a peripheral domain that shuttles its charged cargo through membrane lipid like a hydrophobic cation. We tested this idea by attaching charged adducts to cysteines introduced into the putative voltage-sensor paddle of Shaker potassium channels and measuring fractional changes in the total gating charge from gating currents. The only residues capable of translocating attached charges through the membrane-electric field are those that serve this function in the native channel. This remarkable specificity indicates that charge movement involves highly specialized interactions between the voltage sensor and other regions of the protein, a mechanism inconsistent with the paddle model.
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1 March 2004
Article|
February 09 2004
Specificity of Charge-carrying Residues in the Voltage Sensor of Potassium Channels
Christopher A. Ahern,
Christopher A. Ahern
Department of Physiology, Jefferson Medical College, Philadelphia, PA 19107
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Richard Horn
Richard Horn
Department of Physiology, Jefferson Medical College, Philadelphia, PA 19107
Search for other works by this author on:
Christopher A. Ahern
Department of Physiology, Jefferson Medical College, Philadelphia, PA 19107
Richard Horn
Department of Physiology, Jefferson Medical College, Philadelphia, PA 19107
Address correspondence to Richard Horn, Department of Physiology, Jefferson Medical College, 1020 Locust Street, Philadelphia, PA 19107. Fax: (215) 503-2073; email: [email protected]
Received:
December 15 2003
Accepted:
January 20 2004
Online ISSN: 1540-7748
Print ISSN: 0022-1295
The Rockefeller University Press
2004
J Gen Physiol (2004) 123 (3): 205–216.
Article history
Received:
December 15 2003
Accepted:
January 20 2004
Citation
Christopher A. Ahern, Richard Horn; Specificity of Charge-carrying Residues in the Voltage Sensor of Potassium Channels . J Gen Physiol 1 March 2004; 123 (3): 205–216. doi: https://doi.org/10.1085/jgp.200308993
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