title: Mechanism of activation of pyruvate dehydrogenase by mitogens in pig lymphocytes.
abstract: 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.
mesh_terms: 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
chemical_list: 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