FIGURE 2.
Store-operated activation is retained upon deletion of first four amino acids of N-terminal conserved region of Orai3. a, amino acid sequence of Orai3 N-terminal deletion mutants. Gray letters represent amino acids within the N terminus of Orai3 that were deleted. Shown are times course of whole cell inward currents at −74 mV activated by passive store depletion of HEK 293 cells coexpressing CFP-STIM1 with YFP-Orai3 ΔN1–46 (b), YFP-Orai3 ΔN1–49 (e), and YFP-Orai3 ΔN1–51 (h) in comparison with wild-type YFP-Orai3. c, f, and i, current/voltage relationship corresponding to b, e, and h, respectively. The mean fast inactivation for 100 ms upon voltage steps from a holding potential of 0 to −90 mV of normalized current traces of CFP-STIM1-mediated YFP-Orai3 ΔN1–46 (d), YFP-Orai3 ΔN1–49 (g), and YFP-Orai3 ΔN1–51 (j) currents is shown. k, block diagram opposing the percentage of maximal store-operated currents (t = 200 s) against the percentage of residual currents after 100 ms upon application of a voltage step to −90 mV of Orai3 and Orai3 deletion mutants (for Orai3 ΔN1–46, p > 0.05 for store-operated currents at t = 200 s as well as residual currents of inactivation at t = 100 ms; for Orai3 ΔN1–47, ΔN1–49, and ΔN1–51, p > 0.05 for store-operated currents at t = 200 s but p < 0.05 for residual currents of inactivation at t = 100 ms) mentioned in this figure. l, block diagram of whole cell inward (−74 mV) and outward (+74 mV) currents of HEK 293 cells coexpressing CFP-STIM1 with YFP-Orai3 ΔN1–46, YFP-Orai3 ΔN1–47, YFP-Orai3 ΔN1–49, and YFP-Orai3 ΔN1–51 upon perfusion with 75 μm 2-APB (for inward as well as outward currents at t = 100 s upon application of 2-APB, p > 0.05). pF, picofarad. Error bars represent S.E.