title: Glutamate-stimulated phosphorylation of a specific protein in P2 fractions of rat cerebral cortex.
abstract: Incubation of P2 fractions from rat cerebral cortex with 32Pi in the presence of L-glutamate caused an increased phosphorylation of a protein with apparent molecular weight of 43,000 (P43) as demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography. This glutamate-stimulated phosphorylation of P43 was already detectable 10 s after the addition of glutamate and was dependent on the concentrations of glutamate in the incubation medium. Other excitatory amino acids such as D-glutamate, L-aspartate, D,L-cysteic acid, L-cysteinesulfinic acid, and D,L-alpha-aminoadipic acid did not stimulate the phosphorylation of P43. In contrast, alpha-ketoglutarate and succinate stimulated the phosphorylation of this protein. Glutamate-stimulated phosphorylation of P43 seemed not to be mediated by either cAMP or cGMP and was inhibited by the presence of Ca2+ in the incubation medium. Experiments performed with metabolic inhibitors indicated that glutamate-stimulated protein phosphorylation is localized in mitochondria. This conclusion is supported by the occurrence of glutamate-stimulated phosphorylation of P43 in mitochondrial fractions from several peripheral tissues. The present results are consistent with the hypothesis that P43 is a component of the pyruvate dehydrogenase complex of mitochondria.
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D003995:Dibutyryl Cyclic GMP / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
chemical_list: D005971:Glutamates; D009419:Nerve Tissue Proteins; C002373:monobutyryl cyclic AMP; D003995:Dibutyryl Cyclic GMP; D018698:Glutamic Acid; D003994:Bucladesine; D002118:Calcium