Control of pyruvate kinase activity by glucagon in isolated hepatocytes
Biochemical and Biophysical Research CommunicationsPublished 1 December 1976
J. P. Riou, T.H. Claus, S.J. Pilkis
Citations76
SJR quartileQ2
SJR score0.75
SNIP0.56
Generate an AI Snapshot to get a quick, structured summary of this paper.
Study Snapshot
ObjectiveStudy objective
MethodsResearch methodology
PopulationPopulation studied
Sample sizeSample sizes
OutcomesStudy outcomes here
ResultsStudy results comes here
LimitationsResearch study limitations comes here
A concise AI-generated summary of the paper will appear here once you click Generate AI Snapshot.
Abstract
Incubation of hepatocytes with 10 nM glucagon led to an increase in the K0.5 for phosphoenolpyruvate for pyruvate kinase measured in homogenates of the cells. Incubation of partially purified rat liver pyruvate kinase with protein kinase and ATP led to a similar result. In addition, both the phosphorylated enzyme and homogenates prepared from cells incubated with glucagon exhibited an apparently decreased sensitivity to stimulation by fructose diphosphate when activity was measured in the presence of physiological concentrations of ATP and alanine. These similarities suggest that the effect of glucagon to inhibit hepatocyte pyruvate kinase may be mediated at least in part by a phosphorylation-dephosphorylation mechanism.
Keywords
MedicineBiochemistry, Genetics and Molecular Biology
Journal of Biological ChemistryPROTEIN MEASUREMENT WITH THE FOLIN PHENOL REAGENT
318,326 Citations1951OliverH. Lowry, NiraJ. Rosebrough +2 more
Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.
Journal of Biological ChemistryHormonal control of cyclic 3':5'-AMP levels and gluconeogenesis in isolated hepatocytes from fed rats
202 Citations1975S.J. Pilkis, T.H. Claus +2 more
Glucagon can stimulate gluconeogenesis from 2 mM lactate nearly 4-fold in isolated liver cells from fed rats; exogenous cyclic adenosine 3':5'-monophosphate (cyclic AMP) is equally effective, but epinephrine can stimulate only 1.5-fold.
European Journal of BiochemistryRegulation of Liver Pyruvate Kinase and the Phosphoenolpyruvate Crossroads
181 Citations1970P. Llorente, Roberto Di Marco +1 more
The hypothesis that an isoenzyme of pyruvate kinase present in liver and kidney has evolved with built-in specific regulatory mechanisms in order to prevent the diversion of phosphoenolpyruvates from its way to glucose in glucoenogenic situations is strongly supported.
Biochimica et Biophysica Acta (BBA) - EnzymologyPhosphorylation of purified rat liver pyruvate kinase by cyclic 3′,5′-AMP-stimulated protein kinase
170 Citations1974Olle Ljungström, Gunilla Hjelmquist +1 more
The results suggest that the L type of rat liver pyruvate kinase belongs to the enzymes whose activity is regulated by phosphorylation-dephosphorylation reactions.
Journal of Biological ChemistryHepatic pyruvate kinase. Regulation by glucagon, cyclic adenosine 3'-5'-monophosphate, and insulin in the perfused rat liver.
169 Citations1976James B. Blair, Michele A. Cimbala +2 more
The changes in the kinetic properties of hepatic pyruvate kinase which follow treating the perfused rat liver with glucagon or cyclic AMP are consistent with the changes observed in the enzyme properties upon phosphorylation in vitro by a clyclicAMP-stimulated protein kinase.
Biochimica et Biophysica Acta (BBA) - EnzymologyRegulation in vitro of rat liver pyruvate kinase by phosphorylation-dephosphorylation reactions, catalyzed by cyclic-AMP dependent protein kinases and a histone phosphatase
106 Citations1976Vincent P. K. Titanji, Örjan Zetterqvist +1 more
Results are consistent with the hypothesis that pyruvate kinase is regulated by phosphorylation-dephosphorylation reactions and full activity was restored when phosphorylated pyruve kinase was dephosphorylated by a histone phosphatase from the soluble fraction of rat liver.
Biochimica et Biophysica Acta (BBA) - EnzymologyComparative kinetic studies on the L-type pyruvate kinase from rat liver and the enzyme phosphorylated by cyclic 3′,5′-AMP-stimulated protein kinase
97 Citations1976Pia Ekman, Ulla Dahlqvist +2 more
The results obtained strongly indicate that phosphorylation of pyruvate kinase may also inhibit the enzyme in vivo, which should be important during gluconeogenesis.
Journal of Biological ChemistryInfluence of Glucagon on the Metabolism of Xylitol and Dihydroxyacetone in the Isolated Perfused Rat Liver
87 Citations1973James B. Blair, David E. Cook +1 more
The observations reported in this communication suggest that the effect of glucagon on gluconeogenesis and glycolysis is the result of a complex interaction rather than regulation of one particular enzyme of the gluconeogenic-glycolytic pathway.
Biochemical and Biophysical Research CommunicationsRapid reciprocal changes of rat hepatic glycolytic enzymes and fructose-1,6-diphosphatase following glucagon and insulin injection in vivo
75 Citations1972O. David Taunton, Fred B. Stifel +2 more
The glucagon effect was associated with a marked increase in hepatic cyclic adenosine 3′,5′-monophosphate (cyclic AMP) concentrations and Insulin did not significantly alter hepatic cycling AMP concentrations.
Biochimica et Biophysica Acta (BBA) - General SubjectsStimulation by glucagon of the incorporation of U-14 C-labeled substrates into glucose by isolated hepatocytes from fed rats
67 Citations1975Thomas H. Claus, Simon J. Pilkis +1 more
Evidence was obtained to support the view that glucagon also increases glutamate production (presumably from endogenous protein) and the stimulation of incorporation into glucose from 20 mM [U-14C] lactate by NH4+ plus glucagon was synergistic, suggesting that glucagons also stimulated the incorporation of labeled substrate into glucose by additional means.