Mitochondrial membranes from fibroblasts of control (WT) and patient fibroblasts (i, immortalised) were solubilised with digitonin and separated on native gradient gels. A BN-PAGE gel stained with Coomassie showing molecular weight marker (BHM) and samples from control and patient (primary fibroblasts, (I)=immortalised fibroblasts) B BN-PAGE gel stained with NADH:NTB reductase activity stain showing molecular weight marker (BHM) and samples from control and patient (primary fibroblasts, (I)=immortalised fibroblasts) C Further complexome analysis of the BN-PAGE gels shown in A and B. Each native lane was cut into even fractions from high to low molecular mass. Proteins in each slice were digested with trypsin and analysed by quantitative mass spectrometry. Shown here are average IBAQ values of all identified subunits from complexes III, I and IV 