Regulation of Oxidative Phosphorylation in the Inner Membrane of Rat Liver Mitochondria by Calcium Ions

Yu. V. Evtodienko¹, T. S. Azarashvili^1*, V. V. Teplova¹, I. V. Odinokova¹, and N.-E. Saris²

¹Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia; E-mail: azarashvily@venus.iteb.serpukhov.su

²Biomedicine Institute, Helsinki University, Finland

^* To whom correspondence should be addressed.

Received November 16, 1999; Revision received March 20, 2000

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The effect of accumulation of Ca²⁺ at physiological concentrations (10^-8-10^-6 M) on the rates of ATP synthesis and hydrolysis in rat liver mitochondria was studied. An addition of 5·10^-7 M Ca²⁺ resulted in the maximal rates of synthesis and hydrolysis of ATP. Decrease in the concentration of Ca²⁺ to 10^-8 M or its increase to 5·10^-6 M inhibited oxidative phosphorylation and ATP hydrolysis. It was found that the rate of oxidative phosphorylation correlated with the phosphorylation level of a 3.5-kD peptide in the mitochondrial inner membrane on varying the Ca²⁺ concentration. The possible regulation of oxidative phosphorylation in mitochondria by Ca²⁺ is discussed.

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KEY WORDS: mitochondria, oxidative phosphorylation, F₀F₁-ATPase, protein kinases, protein phosphorylation, calcium

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