Mechanism of activation of pyruvate dehydrogenase by mitogens in pig lymphocytes.
The activity of pyruvate dehydrogenase in extracts of pig mesenteric lymphocytes was measured under different preincubation conditions. The mitogens concanavalin A and ionophore A23187 both increased pyruvate dehydrogenase activity. In both cases activation required extracellular Ca2+. Digitonin-permeabilized cells required 0.5 microM free Ca2+ for half-maximal activation of pyruvate dehydrogenase. The stimulation by concanavalin A in intact cells was probably not due to changes in effectors of pyruvate dehydrogenase kinase. This evidence suggests that activation of pyruvate dehydrogenase is by Ca2+ activation of pyruvate dehydrogenase phosphatase and supports the view that the cytoplasmic free [Ca2+] rises to something less than 1 microM on stimulation with mitogens.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D003208:Concanavalin A / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D066298:In Vitro Techniques; D008213:Lymphocyte Activation / Q000187:drug effects; D008214:Lymphocytes / Q000201:enzymology*; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D011769:Pyruvate Dehydrogenase (Lipoamide)-Phosphatase / Q000378:metabolism; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism*; D013552:Swine
D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D011768:Pyruvate Dehydrogenase Complex; D003208:Concanavalin A; D000001:Calcimycin; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011769:Pyruvate Dehydrogenase (Lipoamide)-Phosphatase; D002118:Calcium