FIGURE 7.

Distal N-terminal region affects channel sensitivity to agonists. Summary histogram of the responses to cold (A) and menthol (B) of the 13 TRPM8 mutants characterized in this part of the study. The values were normalized to the mean response observed on mM8-myc (control condition) in parallel experiments. Black column represents the mM8-myc value; white columns correspond to mutants that displayed a behavior similar to mM8-myc (control); and red columns represent mutants with an enhanced phenotype similar to Δ5–39 (10–20 HA, n = 166; 20–30HA, n = 249; 30–40 HA, n = 277; 19–25 HA, n = 95; 22–28 HA, n = 132; 24–30 HA, n = 122; SS2627VP, n = 84; S26V, n = 180; S27P, n = 166; S27A, n = 88; S2D, n = 109; S26P, n = 166; S26D, n = 90). Values in Δ5–39 (striped red) from Fig. 4 are displayed as reference. C, bar histogram of mean shift in temperature threshold displayed by each mutant referred to mM8-myc values. Positive values indicate shifts to warmer temperatures (same n as in A and B). A–C, statistical significance was assessed by an ANOVA test in combination with a Dunnett's post hoc test: *, p < 0.05; **, p < 0.01; ***, p < 0.001. D, quantification of Western blot experiments. Band intensities from at least three independent experiments were quantified and normalized to GAPDH expression as protein loading control. Levels were quantified relative to mM8-myc expression set at 1.0 (n >3 for all the constructs).