Mitochondrial alpha-ketoacid dehydrogenase kinases: a new family of protein kinases

Adv Second Messenger Phosphoprotein Res. 1997;31:105-11.

Abstract

Four mitochondrial protein kinases have been cloned. These proteins represent a new family of protein kinases, related by sequence to the bacterial protein kinases but by function to the eukaryotic serine protein kinases. Arg288 is required for recognition by BCKDK of the phosphorylation site on the E1alpha subunit of the BCKDH complex. BCKDK inhibits the dehydrogenase activity of the BCKDH complex by introducing a negative charge into the active-site pocket of the E1 component. Protein starvation of rats induces an increase in the amount of BCKDK bound to the BCKDH complex. This causes inactivation of the BCKDH complex and conserves branched-chain amino acids for protein synthesis in the protein-starved state. Expression of the different PDK isoenzymes is tissue specific, and the different PDK isoenzymes are unique with respect to kinetic parameters for ATP and ADP and sensitivity to allosteric effectors (NADH, NAD+, coenzyme A, acetyl-CoA, pyruvate, and dichloroacetate). Preliminary experiments indicate that an increased amount of PDK2 protein partly explains the increase in PDK activity that occurs in rat liver in response to chemically induced diabetes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Humans
  • Mitochondria / enzymology*
  • Mitochondria, Liver / enzymology
  • Mutagenesis, Site-Directed
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Protein-Serine-Threonine Kinases
  • Pyruvate Dehydrogenase (Acetyl-Transferring) Kinase
  • Rats

Substances

  • PDK2 protein, human
  • Pdk2 protein, rat
  • Pyruvate Dehydrogenase (Acetyl-Transferring) Kinase
  • Protein Kinases
  • Protein-Serine-Threonine Kinases
  • (3-methyl-2-oxobutanoate dehydrogenase (lipoamide)) kinase