FIG. 3.

MondoA associates with an OMM protein. (A) Mitochondria were prepared from K562 cells and were mock treated or incubated with proteinase K in the presence or absence of Triton X-100 as indicated. Levels of MondoA, the outer membrane marker porin, and the intermembrane space marker cytochrome c were determined by Western blotting. WCE, whole cell extract; Mito; mitochondrial fraction. (B) Isolated mitochondria from K562 cells were incubated with a cytoplasmic lysate containing MondoA-TAP in the presence of increasing KCl concentrations. After binding and washing, the amounts of MondoA, MondoA-TAP, and aconitase that remained associated with mitochondria were determined by Western blotting. (C) Isolated mitochondria were left untreated (NT), treated with PMSF, treated with proteinase K followed by PMSF, or treated with PMSF followed by proteinase K. Treated mitochondria were incubated with a cytoplasmic lysate containing MondoA-TAP. Following binding and washing of the mitochondrial pellets, the amount of MondoA, MondoA-TAP (bound), or porin (Mito Input) that remained associated with mitochondria following each treatment was determined by Western blotting.