Fig. 3.

Apparent affinities of TRPM2 for both ADPR and Ca²⁺ are strongly temperature dependent. A–D, Macroscopic T5L TRPM2 currents at (A, B) 14°C and (C, D) 40°C, evoked by (A, C) 32 μM ADPR (gray bars) and various concentrations of Ca²⁺ (black bars, [Ca²⁺] in μM), or (B, D) saturating Ca²⁺ (black bars) and various concentrations of ADPR (gray bars, [ADPR] in μM). [Ca²⁺] was 477 and 107 μM, respectively, at 14°C and 40°C; V_m was −80 mV. E, F, Dose–response curves at 14°C (blue symbols) and 40°C (red symbols) of macroscopic T5L TRPM2 currents for (E) Ca²⁺ and (F) ADPR, with the other ligand kept saturated. Currents were normalized to the mean of the currents observed during bracketing exposures to saturating Ca²⁺ + ADPR in the same patch. Data in E, F represent mean ± SEM, n = 4–20 (E, blue), 6–9 (E, red), 3–10 (F, blue), 4–12 (F, red). Colored curves are fits to the Hill equation with fit parameters plotted in the panels.