Key result
Residues near the top of S3 in the Shaker K+ channel did not exhibit any change in aqueous exposure during the gating cycle, arguing against large-scale movements of the voltage-sensor paddle.
The lack of state-dependent changes in aqueous exposure of S3 residues in the Shaker K+ channel argues against large-scale movements of the S3-S4 voltage-sensor paddle during gating.
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Questions paddle model of Kv gating; leaves open conformational details of voltage sensing in cardiac ion channels.
Darman et al. (2006) studied this question. Pore-blocking maleimide reagent and tethered biotin was evaluated on Aqueous exposure of residues near S3 during the gating cycle. Residues near the top of S3 in the Shaker K+ channel did not exhibit any change in aqueous exposure during the gating cycle, arguing against large-scale movements of the voltage-sensor paddle.