Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.2 (PDK1)
 2,238 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antibodies were raised in rabbits to free rat liver pyruvate dehydrogenase (PDH) kinase alpha-chain and shown to react with PDH kinase alpha-chain in rat heart and liver PDH complexes, in purified pig heart PDH complex and in bovine kidney dihydrolipoamide acetyltransferase-protein X-PDH kinase subcomplex. E.l.i.s.a for PDHE1 (pyruvate dehydrogenase) and PDH kinase have been developed and applied to assays of these proteins in extracts of rat liver and rat heart mitochondria; the measured immunoreactivities for PDHE1 (heart > liver) and for PDH kinase alpha-chain (liver > heart) paralleled known differences in PDH complex and PDH kinase activities respectively. The results of e.l.i.s.a of PDH kinase alpha-chain in extracts of rat liver mitochondria showed that the effects of starvation to increase PDH kinase activity in vivo, and the effects of dibutyryl cyclic AMP or palmitate to increase PDH kinase activity in hepatocytes cultured in vitro, are due largely (> 90%) to an increase in the specific activity of PDH kinase. The effect, in cultured hepatocytes, of dibutyryl cyclic AMP to increase PDH kinase activity was blocked by cycloheximide; the effect of palmitate was blocked by an inhibitor of carnitine palmitoyltransferase I (Etomoxir), but not by cycloheximide.
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PMID:Role of protein synthesis and of fatty acid metabolism in the longer-term regulation of pyruvate dehydrogenase kinase. 801 Sep 47

Activity of the mammalian pyruvate dehydrogenase complex is regulated by phosphorylation-dephosphorylation of three specific serine residues (site 1, Ser-264; site 2, Ser-271; site 3, Ser-203) of the alpha subunit of the pyruvate dehydrogenase (E1) component. Phosphorylation is carried out by four pyruvate dehydrogenase kinase (PDK) isoenzymes. Specificity of the four mammalian PDKs toward the three phosphorylation sites of E1 was investigated using the recombinant E1 mutant proteins with only one functional phosphorylation site present. All four PDKs phosphorylated site 1 and site 2, however, with different rates in phosphate buffer (for site 1, PDK2 > PDK4 approximately PDK1 > PDK3; for site 2, PDK3 > PDK4 > PDK2 > PDK1). Site 3 was phosphorylated by PDK1 only. The maximum activation by dihydrolipoamide acetyltransferase was demonstrated by PDK3. In the free form, all PDKs phosphorylated site 1, and PDK4 had the highest activity toward site 2. The activity of the four PDKs was stimulated to a different extent by the reduction and acetylation state of the lipoyl moieties of dihydrolipoamide acetyltransferase with the maximum stimulation of PDK2. Substitution of the site 1 serine with glutamate, which mimics phosphorylation-dependent inactivation of E1, did not affect phosphorylation of site 2 by four PDKs and of site 3 by PDK1. Site specificity for phosphorylation of four PDKs with unique tissue distribution could contribute to the tissue-specific regulation of the pyruvate dehydrogenase complex in normal and pathophysiological states.
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PMID:Site specificity of four pyruvate dehydrogenase kinase isoenzymes toward the three phosphorylation sites of human pyruvate dehydrogenase. 1148

This review summarizes the recent developments on the regulation of human pyruvate dehydrogenase complex (PDC) by site-specific phosphorylation by four kinases. Mutagenic analysis of the three phosphorylation sites of human pyruvate dehydrogenase (E1) showed the site-independent mechanism of phosphorylation as well as site-independent dephosphorylation of the three phosphorylation sites and the importance of each phosphorylation site for the inactivation of E1. Both the negative charge and size of the group introduced at site 1 were involved in human E1 inactivation. Mechanism of inactivation of E1 was suggested to be site-specific. Phosphorylation of site 1 affected E1 interaction with the lipoyl domain of dihydrolipoamide acetyltransferase, whereas phosphorylation site 3 appeared to be closer to the thiamine pyrophosphate (TPP)-binding region affecting coenzyme interaction with human E1. Four isoenzymes of pyruvate dehydrogenase kinase (PDK) showed different specificity for the three phosphorylation sites of E1. All four PDKs phosphorylated sites 1 and 2 in PDC with different rates, and only PDK1 phosphorylated site 3. PDK2 was maximally stimulated by the reduction/acetylation of the lipoyl groups of E2. Presence of the multiple phosphorylation sites and isoenzymes of PDK is important for the tissue-specific regulation of PDC under different physiological conditions.
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PMID:Regulation of mammalian pyruvate dehydrogenase complex by phosphorylation: complexity of multiple phosphorylation sites and kinases. 1179 79

The four pyruvate dehydrogenase kinase (PDK) and two pyruvate dehydrogenase phosphatase (PDP) isoenzymes that are present in mammalian tissues regulate activity of the pyruvate dehydrogenase complex (PDC) by phosphorylation/dephosphorylation of its pyruvate dehydrogenase (E1) component. The effect of lipoic acids on the activity of PDKs and PDPs was investigated in purified proteins system. R-lipoic acid, S-lipoic acid and R-dihydrolipoic acid did not significantly affect activities of PDPs and at the same time inhibited PDKs to different extents (PDK1>PDK4 approximately PDK2>PDK3 for R-LA). Since lipoic acids inhibited PDKs activity both when reconstituted in PDC and in the presence of E1 alone, dissociation of PDK from the lipoyl domains of dihydrolipoamide acetyltransferase in the presence of lipoic acids is not a likely explanation for inhibition. The activity of PDK1 towards phosphorylation sites 1, 2 and 3 of E1 was decreased to the same extent in the presence of R-lipoic acid, thus excluding protection of the E1 active site by lipoic acid from phosphorylation. R-lipoic acid inhibited autophosphorylation of PDK2 indicating that it exerted its effect on PDKs directly. Inhibition of PDK1 by R-lipoic acid was not altered by ADP but was decreased in the presence of pyruvate which itself inhibits PDKs. An inhibitory effect of lipoic acid on PDKs would result in less phosphorylation of E1 and hence increased PDC activity. This finding provides a possible mechanism for a glucose (and lactate) lowering effect of R-lipoic acid in diabetic subjects.
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PMID:R-lipoic acid inhibits mammalian pyruvate dehydrogenase kinase. 1551 96

Pyruvate dehydrogenase (PDH), the first component of the human pyruvate dehydrogenase complex, has two isoenzymes, somatic cell-specific PDH1 and testis-specific PDH2 with 87% sequence identity in the alpha subunit of alpha(2) beta(2) PDH. The presence of functional testis-specific PDH2 is important for sperm cells generating nearly all their energy from carbohydrates via pyruvate oxidation. Kinetic and regulatory properties of recombinant human PDH2 and PDH1 were compared in this study. Site-specific phosphorylation/dephosphorylation of the three phosphorylation sites by four PDH kinases (PDK1-4) and two PDH phosphatases (PDP1-2) were investigated by substituting serines with alanine or glutamate in PDHs. PDH2 was found to be very similar to PDH1 as follows: (i) in specific activities and kinetic parameters as determined by the pyruvate dehydrogenase complex assay; (ii) in thermostability at 37 degrees C; (iii) in the mechanism of inactivation by phosphorylation of three sites; and (iv) in the phosphorylation of sites 1 and 2 by PDK3. In contrast, the differences for PDH2 were indicated as follows: (i) by a 2.4-fold increase in binding affinity for the PDH-binding domain of dihydrolipoamide acetyltransferase as measured by surface plasmon resonance; (ii) by possible involvement of Ser-264 (site 1) of PDH2 in catalysis as evident by its kinetic behavior; and (iii) by the lower activities of PDK1, PDK2, and PDK4 as well as PDP1 and PDP2 toward PDH2. These differences between PDH2 and PDH1 are less than expected from substitution of 47 amino acids in each PDH2 alpha subunit. The multiple substitutions may have compensated for any drastic alterations in PDH2 structure thereby preserving its kinetic and regulatory characteristics largely similar to that of PDH1.
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PMID:Characterization of testis-specific isoenzyme of human pyruvate dehydrogenase. 1643 77