FIGURE 2.

Cooperative interaction between STIM1 fragments and the N and C termini of Orai1 controls channel activation. A, representative plots of the current-voltage relationship of currents recorded from cells expressing the indicated single or double Orai1-SS mutants. pF, picofarad. B, summary of current densities (n = 5–8 cells) or basal Ca²⁺ levels (n = 25–35 cells) recorded from cells expressing Orai1-SS with the indicated single or double mutations. Dashed red columns show the predicted additive effect for the double mutants. C and D, quantitation of expression levels for the Orai1 constructs used in this work. C, summary of fluorescence densities measured for the indicated Orai1-SS-EGFP mutants (n = 6 regions in each). D, representative fluorescence images of cells co-expressing the indicated Orai1-SS-EGFP mutant together with td-Tomato (as a marker for the cytosol and nucleus regions). *, p < 0.05.