Fig. 6.

Impact of palmitoylation on Ca(v)1.2-mediated currents. HEK cells stably expressing wild-type or unpalmitoylatable α1C and transfected with β2a were voltage-clamped at −60 mV. 500-ms voltage steps from −60 mV to +60 mV at 10-mV increments were applied at 1 Hz. Representative examples of currents from wild-type (black) or unpalmitoylatable (red) channels with either Ba²⁺ (A) or Ca²⁺ (B) as the charge carrier are shown. Prominent inactivation was noted with Ca²⁺ as the charge carrier. Peak amplitudes from the families of currents shown in A and B were normalized to cell capacitance and plotted against the step voltage to construct the current–voltage relationships for experiments conducted with Ba²⁺ (C; wild-type N = 14, unpalmitoylatable N = 12) or Ca²⁺ (D; wild-type N = 27, unpalmitoylatable N = 24) as the charge carrier. Current densities at each step voltage were compared between wild-type and unpalmitoylatable channels; **P < 0.01, ***P < 0.001 (unpaired t test with Holm–Sidak correction for multiple comparisons). A Boltzmann function was fitted to the I–V relationships (Methods) to yield Gmax, Vrev, V50, and Ka parameters. The tables provide the parameters derived from individual cells, with P values obtained from unpaired t tests. G–V curves were drawn by calculating G/Gmax (using parameters obtained from the Boltzmann fits of I–V curves from individual cells, see Methods) for Ca(v)1.2 composed of wild-type or unpalmitoylatable α1C with Ba²⁺ (E) or Ca²⁺ (F) as the charge carrier. (G) Time constant for current decay for Ca(v)1.2 at +20 mV for wild-type (N = 24) and unpalmitoylatable (N = 26) α1C.