FIGURE 6.

The Orai1^V102I-CRAC channel is potentiated by negative voltages. A, Orai1^WT-CRAC current did not increase at –100 mV, after equilibration in 10 mm Ca²⁺ and 0 mV holding potential. B, I/V values recorded immediately after the voltage steps shown in A. C, replacement of Na⁺ with NMDG⁺ did not affect the Orai1^WT-CRAC current in 10 mm Ca²⁺. D, potentiation of the Orai1^V102I -CRAC current during hyperpolarizing voltage steps, after equilibration in 10 mm Ca²⁺. E, I/V values were recorded immediately after the voltage steps in D. Inset, scaled I/Versus of Orai1^V102I-CRAC and Orai1^WT-CRAC for comparison. Orai1^V102I-CRAC shows steeper voltage dependence then Orai1^WT-CRAC. F, voltage potentiation of Orai1^V102I-CRAC current in DVF. G, current difference between the beginning and the end of 350-ms voltage steps in 10 mm Ca²⁺ at different voltages is plotted versus voltage. The current was potentiated by potentials lower than 20 mV. H, replacement of Na⁺ with NMDG⁺ did not affect the Orai1^V102I-CRAC current in 10 mm Ca²⁺, demonstrating preserved selectivity for Ca²⁺. I, maximal currents at –100 mV in 10 Ca²⁺ of Orai1^WT-CRAC (n = 6), Orai1^V102I-CRAC before (n = 9), and after voltage-dependent potentiation (n = 5).