The role of mitochondria in modifying calcium-sensitive cytoplasmic metabolic activities. Modification of pyruvate kinase activity.
1. The modification of pyruvate kinase activity in vitro was examined by altering the environmental [Mg(2+)]/[Ca(2+)] ratio with EDTA on the one hand and isolated rat liver mitochondria on the other. 2. Controlled additions of Ca(2+) and EDTA caused pyruvate kinase activity to be alternately and rapidly switched on and off. 3. By being able to accumulate Ca(2+) in preference to Mg(2+) rat liver mitochondria were able to alter the [Mg(2+)]/[Ca(2+)] ratio in the vicinity of pyruvate kinase and thereby modify the activity of this enzyme. 4. The possible role of mitochondria in modifying pyruvate kinase and other ion-sensitive cytoplasmic enzyme activities is discussed.
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000494:pharmacology*; D003593:Cytoplasm / Q000201:enzymology*; D004492:Edetic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008930:Mitochondria, Liver / Q000201:enzymology* / Q000378:metabolism; D011770:Pyruvate Kinase / Q000378:metabolism*; D011817:Rabbits; D051381:Rats
D004492:Edetic Acid; D011770:Pyruvate Kinase; D008274:Magnesium; D002118:Calcium