Fig 4. Upon chemical inhibition of respiration, TbIF1 prevents the establishment of a new F_oF₁-ATPase mediated Δψm.

(A) and (D) The in situ dissipation of the Δψm in response to chemical treatment by NaCN was measured using the safranine O dye in the following cell lines: 29–13 (black line), TbIF1 RNAi noninduced (NON, grey line), TbIF1 RNAi induced for 2 and 4 days (IND2 and IND4, red lines), TbIF1 OE noninduced (NON, dark blue line) and TbIF1 OE induced for 2 days (IND2, light blue line). The reaction was initiated with digitonin (50 μM), whereas NaCN (50 μM) and FCCP (20 μM) were added when indicated. (means ± s.d.; n = 3). (B) and (E) The assay described for (A) and (D) was used to observe the dissipation of the Δψm when the same cells were simultaneously treated with 50 μM NaCN and 2.5 μg/ml oligomycin (NaCN+OM). (means ± s.d.; n = 3). (C) and (F) Changes in safranine O fluorescence after the addition of either NaCN or NaCN+OM to the cell lines outlined above. *** p < 0.0002, Student’s t test.