Figure 3.

2-APB-mediated current density responses in HEK cells stably overexpressing STIM1 with internal Ca²⁺ clamped to 200 nM and no store depletion. (A) CD development over time with Orai1 overexpression (n = 9) and application of 50 μM 2-APB as indicated. Corresponding IV relationship in inset on the upper left. (B) Same experimental setting as in (A) but with Orai3 overexpression (n = 8). (C) Same experimental setting as in (A) but with overexpression of concatenated tetrameric Orai1/Orai3 channels or empty vector as a control (1-1-1-1, n = 7; 3-1-1-1, n = 5; 3-1-1-3, n = 9; 3-1-3-1, n = 8; 3-1-3-3, n = 5; control, n = 6). (D) Corresponding IV relationships extracted from cells in (C). (E) Analysis of 2-APB-mediated outward currents from (C) at t = 178 s. Statistical significance was determined by an unpaired t test with Welch’s correction and is indicated as ns p > 0.05, * p < 0.05, ** p < 0.005, *** p < 0.001.