Disruption of mitochondrial membranes by the SMA copolymer. (A) Schematic of mitochondrial subcompartments and location of protein complexes analyzed in this study. Subunits of the TIM23 Complex and respiratory Complex II (cyan) were analyzed by immunodetection and respiratory Complex IV (green) was analyzed for enzyme activity. (B-D) Time course measurements of TMRM fluorescence were conducted with the addition of the following to actively respiring mitochondria: (B) DDM (final concentration 0.4% (w/v), (C) the SMA copolymer (final concentration 1 g SMA : 1 g mitochondrial protein), and (D) SMA buffer only. Valinomycin was added at the end of each time course to completely collapse the membrane potential.