Fig. 4: The N-terminal end containing an Ankyrin Repeat 1 determines the heat-activation threshold of axolotl and rat TRPV1.

a Schematic representation of TRPV1 chimeras. Chimeric channels were generated between rat (black) and axolotl TRPV1 (Blue) on the basis of the location of the ankyrin repeats (A1–A6) and transmembrane domains (M1–M6). b AR chimera or axTRPV1 was expressed in Xenopus oocytes and the representative heat-induced currents were examined by the two-electrode voltage clamp method as indicated. c ARAC chimera (ARAC1-5) or rTRPV1 was expressed in Xenopus oocytes and the representative heat-induced currents were standardized by the capsaicin-induced currents at 5 μM were indicated. Average current for heat stimulation at 38 °C standardized by the capsaicin-induced currents of each chimera in oocytes were compared (n = 5). Each data point represents the mean ± SE. Statistically significant differences were determined by one-way ANOVA with Tukey–Kramer multiple comparison method, and different letters (a or b) indicate significant differences between the six groups (p < 0.0001). Source data are provided as a Source Data file. d Chimera (ARAC1, RAAC1), axTRPV1, or rTRPV1 was expressed in HEK293T cells and the heat response was analyzed by the whole cell patch-clamp method. Superimposed representative temperature-response relationships are indicated. The threshold for heat-activation of the chimeras (ARAC1, RAAC1), axTRPV1, or rTRPV1 in HEK293T cells were measured as described in the Methods section. The average thresholds were compared (n = 6 for axTRPV1 and ARAC1, n = 5 for RAAC1, n = 4 for rTRPV1). Each data point represents the mean ± SE. Statistically significant differences were determined by one-way ANOVA with Tukey–Kramer multiple comparison method and different letters (a or b) indicate significant differences between the four groups (p < 0.001). Source data are provided as a Source Data file.