Interconversion of phospho- and dephospho- forms of pig heart pyruvate dehydrogenase.

Studies of the effects of beta-adrenergic agonists on the regulation of pyruvate dehydrogenase in the perfused rat heart.

The effects of &adrenergic agonists (e.g. epinephrine and isoproterenol) on the metabolic flux through, and the activation state of the pyruvate dehydrogenase multienzyme complex, were investigated in the isolated perfused rat heart. Infusion of epinephrine caused an inhibition of pyruvate decarboxylation at low (0.1 m ~ ) pyruvate concentrations in the perfusion medium, a stimulation of flux a...

Purification and properties of the phospho and dephospho forms of yeast NAD-dependent glutamate dehydrogenase.

Control by phosphorylation.

The two examples of phospho and dephospho proteins for which structural data were previously available (glycogen phosphorylase and isocitrate dehydrogenase) demonstrated two different mechanisms for control. In glycogen phosphorylase, activation by phosphorylation results in long-range allosteric changes. In isocitrate dehydrogenase, inhibition by phosphorylation is achieved by an electrostatic...

Role of Ca2+ in pyruvate dehydrogenase interconversion in brain mitochondria and synaptosomes.

The steady-state content of active (dephospho) pyruvate dehydrogenase (PDHA) of suspensions of coupled rat brain mitochondria oxidizing succinate was found to be markedly increased with increasing free Ca2+ ion concentration of the medium, with a half-maximal effect at 10(-6.43) M Ca2+. Other ions were present in these studies at concentrations appropriate for the cytosol. Depolarization of the...

Phosphorylation of additional sites on pyruvate dehydrogenase inhibits its re-activation by pyruvate dehydrogenase phosphate phosphatase.

The phosphorylation of sites additional to an inactivating site inhibits the formation of active pig heart pyruvate dehydrogenase complex from inactive pyruvate dehydrogenase phosphate complex by pig heart pyruvate dehydrogenase phosphate phosphatase.