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Properties of deactivation gating currents in Shaker channels.

ABSTRACT: The charge versus voltage relation of voltage-sensor domains shifts in the voltage axis depending on the initial voltage. Here we show that in nonconducting W434F Shaker K(+) channels, a large portion of this charge-voltage shift is apparent due to a dramatic slowing of the deactivation gating currents, Ig(D) (with ? up to 80 ms), which develops with a time course of ?1.8 s. This slowing in Ig(D) adds up to the slowing due to pore opening and is absent in the presence of 4-aminopyridine, a compound that prevents the last gating step that leads to pore opening. A remaining 10-15 mV negative shift in the voltage dependence of both the kinetics and the charge movement persists independently of the depolarizing prepulse duration and remains in the presence of 4-aminopyridine, suggesting the existence of an intrinsic offset in the local electric field seen by activated channels. We propose a new (to our knowledge) kinetic model that accounts for these observations.

SUBMITTER: Lacroix JJ

PROVIDER: S-EPMC3043211 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature

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Properties of deactivation gating currents in Shaker channels.

Lacroix Jérôme J JJ Labro Alain J AJ Bezanilla Francisco F

Biophysical journal 20110301 5

The charge versus voltage relation of voltage-sensor domains shifts in the voltage axis depending on the initial voltage. Here we show that in nonconducting W434F Shaker K(+) channels, a large portion of this charge-voltage shift is apparent due to a dramatic slowing of the deactivation gating currents, Ig(D) (with τ up to 80 ms), which develops with a time course of ∼1.8 s. This slowing in Ig(D) adds up to the slowing due to pore opening and is absent in the presence of 4-aminopyridine, a compo ...[more]

PMID: 21354387

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