Figure 7

Quantitative analysis of STIM1 clustering after ER store depletion. (a) Example of Voronoi tessellation analysis. STIM1 localizations in a cell stimulated with TG are shown at top left, and, for the same region of interest, Voronoi cells from ClusterViSu analysis⁴², the corresponding Voronoi density map, and segmentation of the image into STIM1 clusters (white areas) together with the original localizations (red pixels). Scale bar is 1 μm. (b) STIM1-PATagRFP cluster diameters, molecules localized per cluster, clusters per μm², and relative cell area occupied by clusters, after TG treatment, in siControl- and siSeptin4/5-treated cells. (c) Clusters defined by ImageJ particle analysis of the region in (a) are in close agreement with those defined by Voronoi tessellation. (d) STIM1 cluster dimensions, molecules localized per cluster, STIM1 clusters per μm² and relative cell area occupied by STIM1 clusters from the ImageJ particle analysis. (b,d): siControl, n = 34; siSeptin, n = 35. Statistical significance was determined using a two-tailed t-test.