Competition between extramitochondrial and intramitochondrial ATP-consuming processes.

G Letko; U Küster

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PubMed · 162025

Competition between extramitochondrial and intramitochondrial ATP-consuming processes.

G Letko·U Küster

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Abstract

The relationship between intra- and extramitochondrial ATP utilization was investigated in liver mitochondria isolated from normally fed, starved and high-protein fed rats. ATP export was provoked by adding a hexokinase-glucose-trap and intramitochondrial ATP consumption by adding ammonia, bicarbonate and ornithine in order to stimulate citrulline synthesis. Both processes compete for ATP produced via oxidative phosphorylation; the rate of citrulline formation declines as the extramitochondrial [ATP]/[ADP] ratio decreases. It is concluded that ATP for adenine nucleotide translocation and that for carbamoyl phosphate synthesis are delivered from a common intramitochondrial pool of adenine nucleotides. In mitochondria from rats with a high-protein diet, citrulline synthesis greatly stimulates the rate of oxidative phosphorylation (about two thirds of state 3 respiration). Under these conditions the intramitochondrial [ATP]/[ADP] ratio is significantly reduced. The intramitochondrial [ATP]/[ADP] ratio is not in thermodynamic equilibrium with the extramitochondrial one.

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Adenine Nucleotides Adenosine Triphosphatases Adenosine Triphosphate Animals Carbamoyl-Phosphate Synthase (Ammonia)Citrulline Dietary Proteins Hexokinase Mitochondria, Liver Oxidative Phosphorylation Rats Starvation Journal Article

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G Letko, U Küster. 1979. Competition between extramitochondrial and intramitochondrial ATP-consuming processes.. https://pubmed.ncbi.nlm.nih.gov/162025/

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Adenine Nucleotides↗