1. Physiological diversity of mitochondrial oxidative phosphorylation.
- Author
-
Benard G, Faustin B, Passerieux E, Galinier A, Rocher C, Bellance N, Delage JP, Casteilla L, Letellier T, and Rossignol R
- Subjects
- Animals, Brain cytology, Citrate (si)-Synthase metabolism, Cytochromes metabolism, Electron Transport physiology, Electron Transport Complex I physiology, Electron Transport Complex II physiology, Electron Transport Complex III physiology, Electron Transport Complex IV physiology, Humans, Kidney cytology, Liver cytology, Male, Mitochondrial Proteins metabolism, Muscles cytology, Myocardium cytology, Rats, Rats, Wistar, Brain metabolism, Kidney metabolism, Liver metabolism, Mitochondria metabolism, Mitochondria ultrastructure, Muscles metabolism, Myocardium metabolism, Oxidative Phosphorylation
- Abstract
To investigate the physiological diversity in the regulation and control of mitochondrial oxidative phosphorylation, we determined the composition and functional features of the respiratory chain in muscle, heart, liver, kidney, and brain. First, we observed important variations in mitochondrial content and infrastructure via electron micrographs of the different tissue sections. Analyses of respiratory chain enzyme content by Western blot also showed large differences between tissues, in good correlation with the expression level of mitochondrial transcription factor A and the activity of citrate synthase. On the isolated mitochondria, we observed a conserved molar ratio between the respiratory chain complexes and a variable stoichiometry for coenzyme Q and cytochrome c, with typical values of [1-1.5]:[30-135]:[3]:[9-35]:[6.5-7.5] for complex II:coenzyme Q:complex III:cytochrome c:complex IV in the different tissues. The functional analysis revealed important differences in maximal velocities of respiratory chain complexes, with higher values in heart. However, calculation of the catalytic constants showed that brain contained the more active enzyme complexes. Hence, our study demonstrates that, in tissues, oxidative phosphorylation capacity is highly variable and diverse, as determined by different combinations of 1) the mitochondrial content, 2) the amount of respiratory chain complexes, and 3) their intrinsic activity. In all tissues, there was a large excess of enzyme capacity and intermediate substrate concentration, compared with what is required for state 3 respiration. To conclude, we submitted our data to a principal component analysis that revealed three groups of tissues: muscle and heart, brain, and liver and kidney.
- Published
- 2006
- Full Text
- View/download PDF