Diversity of the Pyruvate Dehydrogenase Kinase Gene Family in Humans

Abstract

) J. Biol. Chem. 269, 29720 -29724). The present study was undertaken to further explore the diversity of the pyruvate dehydrogenase kinase gene family. Here we report the deduced amino acid sequences of three isoenzymic forms of PDK found in humans. In terms of their primary structures, two isoenzymes identified in humans correspond to rat PDK1 and PDK2, whereas a third gene (PDK3) encodes for a new isoenzyme that shares 68% and 67% of amino acid identities with PDK1 and PDK2, respectively. PDK3 cDNA expressed in Escherichia coli directs the synthesis of a polypeptide with a molecular mass of approximately 45,000 Da that possesses catalytic activity toward kinase-depleted pyruvate dehydrogenase. PDK3 appears to have the highest specific activity among the three isoenzymes tested as recombinant proteins.Tissue distribution of all three isoenzymes of human PDK was characterized by Northern blot analysis. The highest amount of PDK2 mRNA was found in heart and skeletal muscle, the lowest amount in placenta and lung. Brain, kidney, pancreas, and liver expressed an intermediate amount of PDK2 (brain > kidney ‫؍‬ pancreas > liver). The tissue distribution of PDK1 mRNA differs markedly from PDK2. The message for PDK1 was expressed predominantly in heart with only modest levels of expression in other tissues (skeletal muscle > liver > pancreas > brain > placenta ‫؍‬ lung > kidney). In contrast to PDK1 and PDK2, which are expressed in all tissues tested, the message for PDK3 was found almost exclusively in heart and skeletal muscle, indicating that PDK3 may serve specialized functions characteristic of muscle tissues. In all tissues tested thus far, the level of expression of PDK2 mRNA was essentially higher than that of PDK1 and PDK3, consistent with the idea that PDK2 is a major isoenzyme responsible for regulation of pyruvate dehydrogenase in human tissues.

Characterization of the porcine differentially expressed PDK4 gene and association with meat quality

“…To date, four isoforms of PDK isoenzymes (PDKs) have been identified in mammals [5,6]. PDKs are mitochondria genes and belong to histidine kinase-like ATPases family.…”

Marked Differences between Two Isoforms of Human Pyruvate Dehydrogenase Kinase

“…Expression Vector Construction-The cloning vectors harboring the human PDK2 and PDK3 cDNA inserts were a kind gift from Kirill M. Popov and Robert A. Harris (6). For PDK2, PCR was performed with Pfu DNA polymerase (Stratagene) using primers that produced a 1.2-kilobase pair product encoding mature PDK2 with a 5Ј NheI site and a 3Ј HindIII site introduced.…”

Nematode pyruvate dehydrogenase kinases: role of the C-terminus in binding to the dihydrolipoyl transacetylase core of the pyruvate dehydrogenase complex

“…In addition, because the nematode trPDKs still seem to be dimers, as judged by chromatography on Superose 12, this C-terminal domain does not seem to be involved in subunit association. A number of conserved domains were identified when the sequences of PDKs from different sources were compared [7]. Interestingly, sequence conservation is present in the C-terminal binding region among all these PDKs (Figure 3).…”

“…Multiple mammalian PDK isoforms have been identified that seem to have unique tissue distributions and physiological roles [5][6][7][8][9]. Interestingly, although these PDK isoforms phosphorylate serine residues, they lack motifs usually present in eukaryotic Ser\Thr kinases and exhibit significant sequence identity with histidine protein kinases best characterized in prokaryotic signal transduction [6,7,10,11].…”

“…Interestingly, although these PDK isoforms phosphorylate serine residues, they lack motifs usually present in eukaryotic Ser\Thr kinases and exhibit significant sequence identity with histidine protein kinases best characterized in prokaryotic signal transduction [6,7,10,11]. PDK activity is enhanced by binding to the E2 core and can be modulated by intramitochondrial ratios of NADH to NAD + and of acetyl-CoA to CoA [9,12].…”