The outermost lysine in the S4 of domain III contributes little to the gating charge in sodium channels.

  title={The outermost lysine in the S4 of domain III contributes little to the gating charge in sodium channels.},
  author={M. Sheets and D. Hanck},
  journal={Biophysical journal},
  volume={82 6},
We investigated the contribution the four outermost basic residues (K1, R2, R3, R4) in segment 4 of domain III in the human cardiac Na channel (hH1a, Na(V)1.5) to the total gating charge (Q(max)). Each of the four basic residues were mutated individually to a cysteine. In addition, R2 was also mutated to a glutamate. All mutant channels were transiently expressed with the alpha1 subunit in fused tsA201 cells. We used the relative reduction in Q(max) caused by anthopleurin-A (ApA) toxin, a site… Expand

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