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Figure S1. Orai1 mutations do not change the requirement of Ca^{2 +} store depletion to occur before CRAC channel activation. (A) Activation of I_CRAC during passive store depletion with a pipette solution containing 8 mM BAPTA. Plots show currents at − 100 mV in cells overexpressing either WT Orai1 or the Orai1 mutant channels. Following maximal activation, currents in cells expressing WT Orai1 often decline, presumably due to elevation of [Ca^{2 +} ]_i and refilling of the Ca^{2 +} stores. (B) Examples of the current–voltage relationships of WT Orai1 and mutant Orai1 currents recorded in 20 mM Ca^{2 +} _o solution.