Figure 2. Crevice facing residues of S1-S3 segments sensitize channel opening to temperature.

Relative open-probability vs voltage-curves for different perturbations at sites S240 (A), E293 (B) and Y323 (C) mutant, deduced from measurements of tail currents at 5mV voltage intervals (see also Fig. S2). Unless otherwise mentioned, in all cases blue curves indicate measurements at 8°C while red curves indicate measurements at 28°C. The mutation corresponding to each panel is listed in the top left corner of each panel. (D) Correlation of temperature dependent change in the median voltage of channel opening (ΔV_M) with the hydrophobicity of perturbation (H-vH scale of biological hydrophobicity (Hessa et al., 2005)) for sites S240 (left panel), E293 (middle panel), Y323 (right panel). The color gradient is used to show the transition from heat (negative ΔV_M) to cold sensitivity (positive ΔV_M) for the spectrum of mutations. (E) Correlation of median voltage of channel opening (V_M) at 28°C, with the hydrophobicity of perturbation for sites S240 (left panel), E293 (middle panel), Y323 (right panel)