Figure 5.

Periodicity of gating perturbations in the S1 segment. (A) Amino acid sequence of the S1 segment in the drk1 K⁺ channel. The bar indicates the stretch used for Fourier transform analysis. (B) The power spectrum of the |ΔΔG ₀| values for this stretch, where P(ω) is plotted as a function of angular frequency (ω). The primary peak of power spectrum occurs at 106°. (C) Helical wheel diagram of these 23 residues viewed from the extracellular side of the membrane. Large shaded circles indicate positions with |ΔΔG ₀| ≥ 1 kcal mol⁻¹ and large open circles indicate positions with |ΔΔG ₀| < 1.0 kcal mol⁻¹. |ΔΔG ₀| values were plotted as vectors on the helical wheel (small open circles); scale is 0–6.9 kcal mol⁻¹. The sum of the |ΔΔG ₀| vectors, represented by the solid circle, has a magnitude of 4.8 kcal mol⁻¹. (D) Helical net diagram for 23 residues with top as extracellular and bottom as intracellular. Open and shaded circles are as in C.