Figure 4

Blue native PAGE of the OXPHOS complexes. In-gel activity staining. In patient 1 (Pearson syndrome), the activity of complex IV is severely decreased in liver. In patient 2 (POLG mutation), complex I and complex II are slightly decreased in skeletal muscle (a limited amount of muscle from the patient was available for testing and the complex II band was weak in the control as well). Normal activities are detected in mitochondria from skeletal muscle of patient 3 (POLG mutation). In liver mitochondria of this patient the activities of complex I, III and IV are slightly decreased. In mitochondria from all patients subcomplexes of complex V are seen (only weakly in patient 2), which is considered as a marker of disturbed intramitochondrial protein synthesis.