Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.31 (AMP-activated protein kinase)
 13,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A modification of the technique of Glyco-Gel affinity column chromatography has been employed to separate glycosylated proteins from nonglycosylated proteins of hemolysates. When glycosylation in hemolysates of 11 type I diabetic subjects was compared with that from 7 normal subjects, significant increases were found in glycosylation of hemoglobin (Hb) (12.1 +/- 6.0% versus 4.7 +/- 0.5%) and purine nucleoside phosphorylase (PNP) (5.3 +/- 3.0% versus 2.1 +/- 0.5%). However, no differences were found for nucleoside diphosphokinase (NDPK) (1.5 +/- 1.1% versus 1.0 +/- 0.4%) and adenylate kinase (AMPK) (0.5 +/- 0.4% versus 0.7 +/- 0.2%). Linear relationships were seen between glycosylated Hb and glycosylated PNP (r = 0.97) or glycosylated NDPK (r = 0.81). On incubation of hemolysates from normal individuals with high glucose (1500 mg/dl or 83 mM) and NaCNBH3 (20 mM), linear increases in the degrees of glycosylation were seen with time. After 18 h, the percentages of glycosylation of Hb, PNP, NDPK, and AMPK were increased from normal values to 31, 24, 11, and 3, respectively. When partially purified human erythrocytic PNP was incubated with various monosaccharides (20 mM) in the presence of NaCNBH3 for 6 h, glycosylation increases of 2-5-fold were seen in the order ribose greater than mannose greater than galactose greater than glucose.
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PMID:Nonenzymatic glycosylation of erythrocytic proteins in normal and diabetic subjects. Enzymes of nucleoside and nucleotide metabolism. 298 81

The AMP-activated protein kinase (AMPK) inhibits several biosynthetic pathways in mammals, and is activated in response to stresses which cause ATP depletion, e.g. heat shock. This system may therefore protect cells against environmental stress by switching off biosynthesis (i.e. growth) to conserve ATP. Recent biochemical and molecular genetic studies have shown that AMPK is closely related to the SNF1 gene product from Saccharomyces cerevisiae, and its homologues in higher plants. SNF1 is required for the response to starvation for glucose. Thus the novel function of providing protection against environmental stress may have evolved from a more ancient response to nutritional stress.
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PMID:Roles of the Snf1/Rkin1/AMP-activated protein kinase family in the response to environmental and nutritional stress. 771 Dec 89

AMP-activated protein kinase is a multisubstrate protein kinase that, in liver, inactivates both acetyl-CoA carboxylase, the rate-limiting enzyme of fatty acid synthesis, and 3-hydroxy-3-methyl-glutaryl-CoA reductase, the rate-limiting enzyme of cholesterol synthesis. AICAR (5-amino 4-imidazolecarboxamide ribotide, ZMP) was found to stimulate up to 10-fold rat liver AMP-activated protein kinase, with a half-maximal effect at approximately 5 mM. In accordance with previous observations, addition to suspensions of isolated rat hepatocytes of 50-500 microM AICAriboside, the nucleoside corresponding to ZMP, resulted in the accumulation of millimolar concentrations of the latter. This was accompanied by a dose-dependent inactivation of both acetyl-CoA carboxylase and 3-hydroxy-3-methylglutaryl-CoA reductase. Addition of 50-500 microM AICAriboside to hepatocyte suspensions incubated in the presence of various substrates, including glucose and lactate/pyruvate, caused a parallel inhibition of both fatty acid and cholesterol synthesis. With lactate/pyruvate (10/1 mM), half-maximal inhibition was obtained at approximately 100 microM, and near-complete inhibition at 500 microM AICAriboside. These findings open new perspectives for the simultaneous control of triglyceride and cholesterol synthesis by pharmacological stimulators of AMP-activated protein kinase.
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PMID:Inhibition of fatty acid and cholesterol synthesis by stimulation of AMP-activated protein kinase. 773 63

In mammals, an AMP-activated protein kinase (AMPK) phosphorylates both acetyl-CoA carboxylase and 3-hydroxy-3-methylglutaryl-CoA reductase in vitro and has been proposed to play a major role in the regulation of lipid metabolism in vivo. We report here the primary sequence of rat AMPK and show that antibodies raised against synthetic peptides based on the deduced sequence of AMPK immunoprecipitate AMPK activity from rat liver extracts. AMPK has a remarkable degree of sequence identity to the proteins encoded by the yeast SNF1 gene and the plant RKIN1 gene. SNF1 protein kinase activity is essential for release of genes from glucose repression in Saccharomyces cerevisiae. Expression of cRKIN1 in yeast snf1 mutants restores SNF1 function. These results indicate that AMPK, SNF1, and RKIN1 form part of a family of protein kinases that have been highly conserved throughout evolution. Our results suggest that AMPK may be involved in the regulation of a wide range of metabolic pathways.
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PMID:Mammalian AMP-activated protein kinase is homologous to yeast and plant protein kinases involved in the regulation of carbon metabolism. 790 7

The product of the SNF1 gene is a protein kinase whose activity is essential for transcriptional activation of glucose repressed genes in Saccharomyces cerevisiae. We have cloned a mammalian AMP-activated protein kinase (AMPK) that is 46% identical to the deduced amino acid sequence of SNF1 (Carling, D., Aguan, K., Woods, A., Verhoeven, A.J.M., Beri, R., Brennan, C.H., Sidebottom, C., Davison, M.D., and Scott, J. (1994) J. Biol. Chem. 269, 11442-11448). Mammalian AMPK plays a major role in the control of lipid metabolism and phosphorylating, thereby inactivating both acetyl-CoA carboxylase and 3-hydroxy-3-methylglutaryl-CoA reductase, key regulatory enzymes in the synthesis of fatty acids and cholesterol, respectively. We present evidence indicating that, in common with its mammalian homologue, SNF1 forms part of a protein kinase cascade. SNF1 is inactivated in vitro by treatment with protein phosphatase 2A and can be reactivated using a partially purified preparation of mammalian AMPK kinase. SNF1 undergoes a time-dependent increase in activity during growth in glucose-derepressing conditions, providing the first evidence that SNF1 activity is regulated by the level of available glucose. In wild-type yeast, but not in a snf1 deletion mutant, acetyl-CoA carboxylase shows a reciprocal change in activity compared with SNF1 under glucose derepressing conditions, indicating that SNF1 regulates acetyl-CoA carboxylase in vivo. These results suggest that, in addition to their structural similarity, the role of SNF1 and AMPK in the regulation of fatty acid synthesis has been highly conserved throughout evolution.
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PMID:Yeast SNF1 is functionally related to mammalian AMP-activated protein kinase and regulates acetyl-CoA carboxylase in vivo. 791 70

In this review, we evaluate the relative regulatory importance of specific strategic enzymes (in particular glycogen synthase, acetyl-CoA carboxylase [ACC] and the pyruvate dehydrogenase complex [PDH]) for carbohydrate utilization as an anabolic precursor and as an energy substrate during the nutritional transitions between the fed and fasted states. The involvement of the specific protein kinases contributing to the inactivation of these enzymes by phosphorylation [cyclic AMP-dependent protein kinase, AMP-activated protein kinase and PDH kinase] in achieving each regulatory response is also assessed. We demonstrate a striking temporal correlation between hepatic glycogen mobilization and PDH and ACC inactivation by phosphorylation during the immediate postabsorptive period; in contrast, rates of hepatic glycogen synthesis and PDH and ACC expressed activities do not change in parallel during refeeding. The results are consistent with shifting of the primary sites of control for overall hepatic carbon flux during the fed-to-starved and starved-to-fed nutritional transitions achieved, at least in part, by a complex pattern of regulation by protein phosphorylation and metabolites which is critically dependent on the precise nutritional status. Data are also presented that demonstrate asynchronous suppression of glucose uptake/phosphorylation and pyruvate oxidation in cardiac and skeletal muscle during progressive starvation. Analogous asynchrony is observed in the reactivation of these processes in cardiac and skeletal muscle during refeeding after starvation. We provide evidence in support of the concept that selective suppression of pyruvate oxidation in oxidative muscles during early starvation and during the initial phase of refeeding is achieved because of differential sensitivity of glucose uptake/phosphorylation and pyruvate oxidation to lipid-fuel utilization. We discuss the relative importance of regulatory events governing local fatty acid production and utilization (via lipoprotein lipase and carnitine palmitoyltransferase 1, respectively) or overall fatty acid supply (dictated by events at the adipocyte) for fuel utilization by muscle during nutritional transitions. Finally, we assess the regulatory importance of glycogen synthesis in determining overall rates of glucose clearance by skeletal muscle during alimentary hyperglycemia and hyperinsulinemia.
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PMID:Mechanisms involved in the coordinate regulation of strategic enzymes of glucose metabolism. 810 32

The mammalian 5'-AMP-activated protein kinase (AMPK) is a heterotrimeric protein consisting of alpha-, beta-, and gamma-subunits. The alpha-subunit is the catalytic subunit and is related to the yeast Snf1p kinase. In this study, we report the cloning of full-length cDNAs for the non-catalytic beta- and gamma-subunits. The rat liver AMPK beta-subunit clone predicts a protein of 30,464 Da, which is related to the Sip1p, Sip2p, and Gal83p subfamily of yeast proteins that interact with Snf1p and are involved in glucose regulation of gene expression. The AMPK beta-subunit, when expressed in bacteria and in mammalian cells, migrates anomalously on SDS gels at an apparent molecular mass of 40 kDa. Rat and human liver AMPK gamma-subunit clones predict a protein of 37,577 Da (AMPK-gamma1), which is related to the yeast Snf4p protein that copurifies with Snf1p and to a larger family of other human AMPK gamma-isoforms. The mRNAs for both AMPK- beta and AMPK-gamma1 are widely expressed in rat tissues, consistent with a broad role for AMPK in cellular regulation. These data reveal a mammalian multisubunit protein kinase strikingly similar to the multisubunit glucose-sensing Snf1 kinase complex. The identification of isoform families for the AMPK subunits indicates the potential diversity of the roles of this highly conserved signaling system in nutrient regulation and utilization in mammalian cells.
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PMID:Non-catalytic beta- and gamma-subunit isoforms of the 5'-AMP-activated protein kinase. 862 99

In newborn rabbits, fatty acid oxidation rates in the heart significantly increase between 1 and 7 days after birth. This is due in part to a decrease in malonyl coenzyme A (CoA) production by acetyl CoA carboxylase (ACC). In other tissues, 5'-AMP-activated protein kinase (AMPK) can phosphorylate and inhibit ACC activity. In this study, we show that 1- and 7-day-old rabbit hearts have a high AMPK activity, with AMPK expression and activity being greatest in 7-day-old hearts. Hearts were also perfused in the Langendorff mode with Krebs-Henseleit buffer containing 0.4 mmol/L [14C]palmitate and 11 mmol/L glucose +/- 100 microU/mL insulin. In the absence of insulin, fatty acid oxidation rates were significantly higher in 7-day-old hearts compared with 1-day-old hearts. AMPK activity was also greater in 7-day-old hearts compared with 1-day-old hearts (909 +/- 60 and 585 +/- 75 pmol.min-1.mg protein-1, respectively; P < .05). In 1-day-old hearts, the presence of insulin resulted in a significant decrease in AMPK activity, an increase in ACC activity, and a decrease in fatty acid oxidation rates. In 7-day-old hearts, AMPK activity was also decreased by insulin, although ACC activity remained low and fatty acid oxidation rates remained high. Stimulation of AMPK in 7-day-old hearts with 200 mumol/L 5-amino 4-imidazolecarboxamide ribotide resulted in a further decrease in ACC activity and an increase in fatty acid oxidation rates. These data suggest that AMPK, ACC, and fatty acid oxidation are sensitive to insulin in 1-day-old rabbit hearts and that the decrease in circulating insulin levels seen after birth leads to an increased activity of AMPK. This can then lead to a phosphorylation and inhibition of ACC activity, with a resultant increase in fatty acid oxidation rates.
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PMID:Upregulation of 5'-AMP-activated protein kinase is responsible for the increase in myocardial fatty acid oxidation rates following birth in the newborn rabbit. 911 78

A single entity, the AMP-activated protein kinase (AMPK), phosphorylates and regulates in vivo hydroxymethylglutaryl-CoA reductase and acetyl-CoA carboxylase (key regulatory enzymes of sterol synthesis and fatty acid synthesis, respectively), and probably many additional targets. The kinase is activated by high AMP and low ATP via a complex mechanism, which involves allosteric regulation, promotion of phosphorylation by an upstream protein kinase (AMPK kinase), and inhibition of dephosphorylation. This protein-kinase cascade represents a sensitive system, which is activated by cellular stresses that deplete ATP, and thus acts like a cellular fuel gauge. Our central hypothesis is that, when it detects a 'low-fuel' situation, it protects the cell by switching off ATP-consuming pathways (e.g. fatty acid synthesis and sterol synthesis) and switching on alternative pathways for ATP generation (e.g. fatty acid oxidation). Native AMP-activated protein kinase is a heterotrimer consisting of a catalytic alpha subunit, and beta and gamma subunits, which are also essential for activity. All three subunits have homologues in budding yeast, which are components of the SNF1 protein-kinase complex. SNF1 is activated by glucose starvation (which in yeast leads to ATP depletion) and genetic studies have shown that it is involved in derepression of glucose-repressed genes. This raises the intriguing possibility that AMPK may regulate gene expression in mammals. AMPK/SNF1 homologues are found in higher plants, and this protein-kinase cascade appears to be an ancient system which evolved to protect cells against the effects of nutritional or environmental stress.
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PMID:The AMP-activated protein kinase--fuel gauge of the mammalian cell? 920 14

5-Aminoimidazole-4-carboxamide ribonucleoside (AICAR) has previously been reported to be taken up into cells and phosphorylated to form ZMP, an analog of 5'-AMP. This study was designed to determine whether AICAR can activate AMP-activated protein kinase (AMPK) in skeletal muscle with consequent phosphorylation of acetyl-CoA carboxylase (ACC), decrease in malonyl-CoA, and increase in fatty acid oxidation. Rat hindlimbs were perfused with Krebs-Henseleit bicarbonate containing 4% bovine serum albumin, washed bovine red blood cells, 200 microU/ml insulin, and 10 mM glucose with or without AICAR (0.5-2.0 mM). Perfusion with medium containing AICAR was found to activate AMPK in skeletal muscle, inactivate ACC, and decrease malonyl-CoA. Hindlimbs perfused with 2 mM AICAR for 45 min exhibited a 2.8-fold increase in fatty acid oxidation and a significant increase in glucose uptake. No difference was observed in oxygen uptake in AICAR vs. control hindlimb. These results provide evidence that decreases in muscle content of malonyl-CoA can increase the rate of fatty acid oxidation.
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PMID:AICA riboside increases AMP-activated protein kinase, fatty acid oxidation, and glucose uptake in rat muscle. 943 25


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