It has become increasingly clear that protein-protein interactions (PPIs) are compartmentalized in nano- scale domains that define the biochemical architec- ture of the cell. Despite tremendous advances in su- per-resolution imaging, strategies to observe PPIs at sufficient resolution to discern their organization are just emerging. Here we describe a strategy in which PPIs induce reconstitution of fluorescent proteins (FPs) that are capable of exhibiting single-molecule fluctuations suitable for stochastic optical fluctuation imaging (SOFI). Subsequently, spatial maps of these interactions can be resolved in super-resolution in living cells. Using this strategy, termed reconstituted fluorescence-based SOFI (refSOFI), we investigated the interaction between the endoplasmic reticulum (ER) Ca2+ sensor STIM1 and the pore-forming chan- nel subunit ORAI1, a crucial process in store-oper- ated Ca2+ entry (SOCE). Stimulating SOCE does not appear to change the size of existing STIM1/ORAI1 interaction puncta at the ER-plasmamembrane junc- tions, but results in an apparent increase in the num- ber of interaction puncta.