title: Apparent identity of alpha-subunit of pyruvate dehydrogenase and the protein phosphorylated in the presence of glutamate in P2-fractions of rat cerebral cortex.
abstract: Addition of L-glutamate or several citric acid cycle intermediates stimulated the phosphorylation of a protein with apparent molecular weight of 43,000 ( P43 ) in P2-fractions from rat cerebral cortex, and this phosphorylation was inhibited by dichloroacetic acid, a specific inhibitor of pyruvate dehydrogenase kinase. Comparison of several molecular properties of phosphorylated P43 and the phosphorylated alpha-subunit of pyruvate dehydrogenase indicated that both proteins are extracted by a similar procedure and have an identical apparent molecular weight and isoelectric point. Furthermore, digestion of both phosphorylated proteins by several different proteases in the presence of SDS yielded a similar pattern of phosphorylated peptides indicating that these proteins have a considerable sequence homology. Thus, various pieces of evidence indicate that P43 and the alpha-chain of pyruvate dehydrogenase are very similar if not identical. The possible implication of a glutamate stimulated phosphorylation of pyruvate dehydrogenase for long term potentiation and epilepsy is discussed.
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002540:Cerebral Cortex / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D008928:Mitochondria / Q000201:enzymology; D008970:Molecular Weight; D009243:NAD / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D051381:Rats; D013574:Synaptosomes / Q000201:enzymology
chemical_list: D005971:Glutamates; D009419:Nerve Tissue Proteins; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D009243:NAD; D018698:Glutamic Acid; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases