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. 2020 Mar 25;152(5):e201912533. doi: 10.1085/jgp.201912533

Figure 5.

Figure 5.

Apparent affinities for channel activation by ADPR of WT nvTRPM2 and MHR1/2 domain mutants. (A–G) Macroscopic inside-out patch currents of WT (A), T143A (B), R271A (C), T307A (D), R329A (E), T179A (F), and Y264A (G) nvTRPM2 activated by increasing concentrations of ADPR (gray bars) in the presence of 125 µM Ca2+ + 2.5 µM PIP2 (black bars). (H) ADPR dose–response curves of fractional currents, normalized to the mean of the currents observed during bracketing applications of saturating ADPR in the same patch, for WT and mutant nvTRPM2 channels (color coding follows construct labeling in A–G). Data represent mean ± SEM from 3 to 17 independent experiments. Colored lines are fits to the Hill equation yielding fit parameters EC50 = 1.5 ± 0.1 µM and nH = 1.7 ± 0.2 for WT, EC50 = 6.3 ± 0.3 µM and nH = 2.6 ± 0.2 for T143A, EC50 = 0.62 ± 0.05 µM and nH = 1.4 ± 0.2 for R271A, EC50 = 31 ± 2 µM and nH = 2.0 ± 0.2 for T307A, EC50 = 1,710 ± 934 µM and nH = 1.3 ± 0.3 for R329A, EC50 = 14 ± 1 µM and nH = 1.9 ± 0.2 for T179A, and EC50 = 1,867 ± 936 µM and nH = 1.4 ± 0.3 for Y264A nvTRPM2.