Fig. 3

Splitting monSTIM1 into two components. A Schematic of the working mechanism of two-component systems. B Schematic of fusion constructs. C Fluorescence images of RGECO1 in HeLa cells co-expressing each pair of proteins (Sets 1–5), illuminated with blue light. D Summary data showing maximum fold changes (ΔF/F0) in RGECO1 intensity upon activation of monSTIM1 variants. E Fluorescence intensity of RGECO1 in the absence of blue light. monSTIM1: n = 52; Set 1: n = 27; Set 2: n = 24; Set 3: n = 14; Set 4: n = 21; Set 5: n = 51 cells. Data are presented as means ± SEM (*p < 0.05, **p < 0.01, ****p < 0.0001; Student two-tailed t test); ns, not significant (p > 0.05)