Fig 1: BN-PAGE for complex IV and OXPHOS Western blot in COX11 fibroblasts. Mitochondria isolated from Patient X1 and control fibroblasts analyzed by BN-PAGE immunoblotting for COX2, COX4, (a) and COX1 (b) suggest a decreased level of monomeric CIV more evident in mitochondria solubilized with Triton X-100, which separates the individual OXPHOS complexes (marked by *); ‡indicates previous COX1 signal and complex II (SDHA) was used as a loading control. (c) The levels of other OXPHOS subunits in isolated mitochondria were similar to controls (CI-NDUFA9, CIII-CORE1, and CV-ATP5A). (d) Representative SDS-PAGE and western blot analysis in whole cell lysates with an antibody cocktail targeting individual OXPHOS complex subunits showed consistently lower levels of CIV in patient X1; porin (VDAC1) was used as a loading control. BN, Blue native; CIV, complex IV; OXPHOS, oxidative phosphorylation; BN-PAGE, Blue native polyacrylamide gel electrophoresis; SDHA, succinate dehydrogenase complex subunit A; SDS, sodium dodecyl sulfate.