Mitochondrial pellet was resuspended in digitonin buffer (30 mM HEPES-KOH, pH 7.4, 150 mM potassium acetate, 10 [v/v] glycerol, and 1 mg of digitonin) and kept on ice for 30 min. Ten microliters of antibody serum, 50 mL of Protein A-Sepharose, 1 (w/v) BSA, and Complete protease inhibitor (Roche) were added to the mitochondria and incubated for 6 h at 4 on a rotating wheel at 20 rpm. Beads were