Fig. 2.

Permeation properties of Orai3-Orai1 tandem. (A) Localization, overlay and FRET of CFP-/YFP-Orai3-Orai1. (B) Time course of Stim1 and Orai3-Orai1 co-expression depicting activation of Ca²⁺ currents upon passive store-depletion, followed by perfusion of a Cs⁺-DVF solution after 200 s. Corresponding representative current voltage relationships were taken from voltage ramps in a (C) 10 mM Ca²⁺, (D) Cs⁺-DVF, or (F) Na⁺–DVF containing bath solution for Stim1 and Orai3-Orai1 expressing cells. (E) Fully activated Ca²⁺ currents of Stim1 and Orai3-Orai1 co-expression are followed by Na⁺-DVF solution. (G) Ca²⁺ current of Stim1 co-expressed with either Orai1, Orai3 or Orai3-Orai1 were activation by store-depletion and Na⁺ and Cs⁺ was substituted by TEA⁺ in the bath solution after 200 s. (H) Time course of currents and (I) current-voltage relationship of a co-expression of STIM1 with either Orai1, Orai3, or Orai3-Orai1 activated by a 10 mM EGTA and K⁺-based pipette solution.