Figure 4

The Ca²⁺-induced rearrangement of MICU1 multimers is independent of the expression level of MCU and EMRE.

(A) Average curves of MICU1 FRET ratio signals over time in response to 100 μM histamine in Ca²⁺-free solution of control HeLa cells (black curve, n = 23) and cells treated with siRNA against MCU (blue curve, n = 22). (B) Bars represent maximal ∆ MICU1 FRET ratio values (mean ± SEM) extracted from curves shown in panel A. (C) Bars represent maximal ∆ MICU1 FRET ratio values upon cell treatment with 100 μM histamine in Ca²⁺-free solution of control HeLa cells (white column, n = 19) and cells treated with siRNA against EMRE (red column, n = 12). (D) Concentration response curves showing the effects of different Ca²⁺ concentrations on the MICU1 FRET ratio in ionomycin- (3 μM) treated control HeLa cells (black curve, white circles, n = 7–9), cells reduced of MCU (blue dotted curve, blue filled squares, n = 8–10) and cells reduced of EMRE (red dotted curve, red filled rhombs, n = 10).