Fig. 2.

Activating mutations in STIM1 prevent SOAR docking to CC1. Activating mutations in the YFP–STIM1(1–343) construct abolish the ability of SOAR to bind the CC1 domain. (A) COS-7 cells were transfected with YFP–STIM1(1–343)D76A and mRFP–SOAR. No ER association of the SOAR domain was observed. (B) YFP–STIM1(1–343)L251S also prevents mRFP–SOAR association with the STIM1 mutant. (C) When the SOAR domain is included in the STIM1 sequence [YFP–STIM1(1–448)] the mRFP–SOAR domain still binds to the STIM1 molecule. However, it is not released during Ca²⁺ store depletion, rather it co-clusters with the STIM1 molecule. We reason that this result reflects a SOAR–SOAR interaction. Here, representative images are shown, but statistical analysis of a large number of cells is shown in Fig. S2. Scale bars: 10 μm.