Calcium indirectly increases the control exerted by the adenine nucleotide translocator over 2-oxoglutarate oxidation in rat heart mitochondria
| Author | Affiliation |
|---|---|
Bakker, Barbara M | E. C. Slater Institute, BioCenter, University of Amsterdam, Amsterdam, The Netherlands |
Brown, Guy C. | University of Cambridge, Cambridge, UK |
Westerhoff, Hans V | Department of Microbial Physiology, Faculty of Biology, Free University, Amsterdam, The Netherlands |
Kholodenko, Boris N | A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia |
| Date |
|---|
1995-12-01 |
The effect of calcium on the control exerted by the adenine nucleotide translocator over respiration in isolated heart mitochondria was investigated in order to determine whether calcium directly stimulates the translocator, At respiration rates intermediate between states 3 and 4, Ca2+ is shown to increase the control over 2-oxoglutarate oxidation exerted by the adenine nucleotide translocator in rat heart mitochondria, This did not occur when succinate was the respiratory substrate, even though the control exerted by the translocator was substantial, indicating that Ca2+ does not have a direct effect on the adenine nucleotide translocator, Ca2+ increased the uncoupled oxidation rate of 2-oxoglutarate, but not succinate, Using the summation theorem for flux control, the effect of Ca2+ is explained by a shift of the control over respiration rate toward the adenine nucleotide translocator, from the respiratory chain, presumably as the result of the activation of the 2-oxoglutarate dehydrogenase complex, (C).