FIGURE 3.

Orai1 activation kinetics are controlled by the N-terminal flexible random coil domains of STIM1 and STIM2. HEK293 stably expressing Orai1 were transiently transfected with STIM1, STIM2, STIM1_S2NT, or STIM2_S1NT. A and B, currents were measured at −100 mV, normalized by their respective cell size, averaged, and plotted versus time ± S.E. Data are presented as normalized average time courses of BAPTA-induced I_CRAC in HEK293 cells expressing STIM1 or STIM1_S2NT (A) or STIM2 or STIM2_S1NT (B). pF, picofarads. C, representative I/V curve measured at peak levels of CRAC current in panels A and B. Data depicted in this figure are based on between 9 and 18 independent measurements.