Extended Data Figure 1. Biophysical characterization of Ca_VAb I199S.

a, Ba²⁺ currents recorded from a holding potential of −120 mV to test potentials from −60 mV to 20 mV in 10 mV steps for I199S. b, G–V curves of Ca_VAb and Ca_VAb I199S derived from peak I–V relationships. The voltages for half-maximal activation and slopes are: Ca_VAb: V_1/2 = − 18.8±0.3, k =3.68±0.43, n = 7; Ca_VAb I199S: V_1/2 = −18.8±0.3, k =3.88±0.47 (n = 5). c, Repetitive depolarization to 0 mV at 1 Hz from a holding potential of − 120mV (n 5). d, Steady-state inactivation of Ca_VAb and Ca_VAb I199S. Two pulses were applied: a 300-ms conditioning pulse to the indicated potentials followed by 50-ms test pulse to 0 mV (n =3). e, State-dependent block of Ca_VAb I199S by 10 nM (green), 100 nM (blue), or 1.5 μM (red) amlodipine during repetitive depolarizations to 0 mV (left, n = 3–5 cells). Ba²⁺ currents in 100 nM amlodipine for Ca_VAb I199S (right). f, Concentration-dependent block of Ca_VAb I199S by nimodipine at 100 nM (blue), 1 μM (red), 5 μM (brown), 10 μM (grey) and 50 μM (black) (left, n = 4–5 cells for each curve). Ba²⁺ currents in the presence of 5 μM nimodipine for Ca_VAb I199S (right).