Fig. 3.

STIM1 ER-to-PM signaling is a local process. (A) YFP-STIM1 diffusion in basal and ionomycin-treated cells monitored by fluorescence recovery after photobleaching measurements. (Scale bar, 10 μm.) (B) The average YFP-STIM1 intensity ratio of two sites inside and outside of the photobleached region (5 μm apart; n = 8 for each condition). (C) A series of relative Gaussian intensity profiles were fit through images such as those shown in A, and the increase in the square of the Gaussian peak radius (a²) was tracked over time to derive an apparent diffusion coefficient. (D) The average diffusion coefficients of YFP-STIM1 before and after Ca²⁺ store depletion (n = 5 for each condition; SEs are shown).