Figure 1. 2-APB decreased V_rev and increased Cs⁺ permeability on STIM1-activated Orai1 channels.

(A) Average I_CRAC evaluated at ± 100 mV in HEK293 cells co-expressing STIM1-mOrange2 and Orai1-mGFP. (B) I-V relationships of I_CRAC and I_p. (C) The bar graph summarizes the V_rev of I_CRAC and I_p. Values are mean ± SEM (n = 8). Compared with I_CRAC, I_p displayed decreased V_rev (p = 0.008). (D,E) Average currents at −100 mV, plotted against time, as the extracellular solution was switched between 2 mM Ca²⁺ and Cs⁺-DVF solution on the WT CRAC channels (n = 7) (D) and 5 μM 2-APB-treated WT CRAC channels (n = 7) (E). I–V relationships of stable Ca²⁺I_CRAC (1, black) and stable Cs⁺ current (2, green) are shown to the right of panels (D,E), respectively. (F) Comparison of the amplitude of Cs⁺-conducted I_CRAC at −100 mV with or without 5 μM 2-APB. Values are mean ± SEM.