Figure 2.

MCU current density as a function of [Ca²⁺]_C, [Ca²⁺]_M, and Δψ. (A) The inverted bell-shaped behavior of the MCU Ca²⁺ flux changes into a biphasic behavior with almost zero and optimal current density at low and high [Ca²⁺]_M respectively as we decrease [Ca²⁺]_C; (B) the ratio of I_MCU/C_m observed at [Ca²⁺]_M = 0 μM to that observed at [Ca²⁺]_M = 0.4 μM in WT mitoplasts at different [Ca²⁺]_C values. (C) raw and (D) normalized I_MCU/C_m (normalized with respect to the minima (maximum Ca²⁺ influx) of the trace) at different [Ca²⁺]_C and [Ca²⁺]_M values as we vary Δψ in WT, MICU1 KO, and MICU2 KO mitoplasts. Thick solid line in (D) represents model fit; (E) I_MCU/C_m given by the model as a function of [Ca²⁺]_M and Δψ at [Ca²⁺]_C = 100 μM. Experimental data shown for comparison is from [19] (B–D).