Fig. 2

Reducing the size of monSTIM1 by truncating STIM1. A Schematic depiction of CRY2-fused STIM1 fragment constructs. Each fusion protein was labeled with EGFP. CC1 and CC2, coiled-coil domains; ERM, ezrin-radixin-moesin domain; D, acidic region; S/P, serine-/proline-rich segment; K, polybasic domain. B Fluorescence images of RGECO1 in HeLa cells co-expressing each CRY2-fused STIM1 fragment (Sets 1–6), illuminated with blue light. C Summary data showing maximum fold changes (ΔF/F₀) in RGECO1 intensity upon activation of monSTIM1 variants. D Fluorescence intensity of RGECO1 in the absence of blue light. monSTIM1: n = 43; Set 1: n = 44; Set 2: n = 74; Set 3: n = 81; Set 4: n = 52; Set 5: n = 48; Set 6: n = 18 cells. E Schematic depiction of CRY2-fused STIM1 fragment constructs whose expression is driven by IRES2. F Fluorescence images of RGECO1 in HeLa cells co-expressing each CRY2-fused STIM1 fragment (Sets 1–7), illuminated with blue light. G Summary data showing maximum fold changes (ΔF/F₀) in RGECO1 intensity upon activation of monSTIM1 variants. H Fluorescence intensity of RGECO1 in the absence of blue light. monSTIM1: n = 42; Set 1: n = 30; Set 2: n = 32; Set 3: n = 43; Set 4: n = 27; Set 5: n = 41; Set 6: n = 26; Set 7: n = 81 cells. Data are presented as means ± SEM (*p < 0.05, ***p < 0.001, ****p < 0.0001; Student two-tailed t test); ns, not significant (p > 0.05)