Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.1.32 (phosphoenolpyruvate carboxykinase)
4,204 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of metabolic acidosis and of hormones on the activity, synthesis, and degradation of renal cytosolic P-enolpyruvate carboxykinase (GTP) (EC 4.1.1.32) were studied in the rat using isotopic -immunochemical procedures. At normal acid-base balance, the synthesis of the enzyme accounted for between 2 and 3.5% of the synthesis of all soluble protein in the kidney cortex. P-enolpyruvate carboxykinase synthesis was selectively stimulated in acute metabolic acidosis, so that the relative rate of synthesis of the enzyme was increased to 7% 13 hours after oral administration of ammonium chloride. The stimulation of P-enolpyruvate carboxykinase synthesis preceded any increase in the assayable activity of the enzyme. The administration of sodium bicarbonate to acutely acidotic rats returned the rate of enzyme synthesis to normal in 8 hours. The effect of acidosis on both the synthesis and the activity of P-enolpyruvate carboxykinase was prevented by actinomycin D, cordycepin, and cycloheximide. The degradation in vivo of pulse-labeled P-enolpyruvate carboxykinase was not affected by acidosis. Thus, the stimulation of P-enolpyruvate carboxykinase synthesis is the major mechanism for the increase in the level of the enzyme observed in metabolic acidosis. The administration of glucocorticoid triamcinolone resulted in an increase in the relative rate of P-enolpyruvate carboxykinase synthesis and a commensurate increase in the activity of the enzyme in the renal cortex. Both changes were abolished by actinomycin D. Fasting was characterized by a high enzyme activity and a rapid rate of enzyme synthesis in the kidney cortex. This high rate of synthesis was reduced after the administration of sodium bicarbonate, but not after glucose feeding. Moreover, the injection of insulin to diabetic rats did not repress P-enolpyruvate carboxykinase synthesis in the renal cortex. Theophylline plus N-6, 0-2'-dibutyryl adenosine 3':5'-monophosphate stimulated P-enolpyruvate carboxykinase synthesis in the kidney of intact rats. However, the latter effect was probably due to glucocorticoid secretion, since it did not occur in adrenalectomized animals. The administration of parathyroid extracts did not result in the induction of the enzyme. Thus, the hormonal regulation of cytosolic P-enolpyruvate carboxykinase synthesis in the kidney differs markedly from that in the liver.
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PMID:The regulation of phosphoenolpyruvate carboxykinase (GTP) synthesis in rat kidney cortex. The role of acid-base balance and glucocorticoids. 16 19

Xenopus laevis (Daudin) adult specimens were submitted to hypophysectomy. Although the operation resulted subtotal, it served the purpose of removing the prolactin-producing cells, whereby the involvement of endogenous prolactin in osmoregulation phenomena was excluded. In the operated animals treated with ovine prolactin the following metabolic parameters, which are closely dependent upon interrenal activity, were estimated: 1) intestine alkaline phosphomonoesterase activity (E.C. 3.1.3.1); 2) liver glycogen level; 3) glucose-6-phosphatase (E.C. 3.1.3.9.) and phosphoenolpyruvate carboxykinase (E.C. 4.1.1.32.) in the liver; 4) blood glucose level; 5) blood ammonia and urea levels; 6) carbamoylphosphate synthetase activity in the liver (E.C. 2.7.2.a); 7) muscle sodium and potassium levels. The above metabolic parameters were found to be pressed by subtotal hypophysectomy and after subsequent prolactin treatment showed the tendency to go back to values similar to those of control animals.
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PMID:Biochemical data on subtotally hypophysectomized Xenopus laevis (Daudin) adult specimens treated or not with prolactin. 21 25

The cytosolic form of phosphoenolpyruvate carboxykinase (GTP; EC 4.1.1.32) from rat liver was purified by a procedure involving affinity chromatography on agarose-hydrazide-GTP. Phosphoenolpyruvate carboxykinase is retained quantitatively by the affinity medium in the presence of manganese and can be specifically eluted by a pulse of GTP. On the contrary, no binding to agarose-hydrazide-GTP occurs in the absence of manganese. This suggests that the affinity of the enzyme for GTP is enhanced by prior interaction with manganese. A combination of several conventional purification steps followed by affinity chromatography provides pure phosphoenolpyruvate carboxykinase in good yields. The final specific activity is 19 U/mg protein. The enzyme migrates as a single polypeptide of molecular weight 70,600 during electrophoresis on sodium dodecyl sulfate polyacrylamide gels.
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PMID:Purification of phosphoenolpyruvate carboxykinase (GTP) by affinity chromatography on agarose-hydrazide-GTP. 52 Feb 80

The influence of protein intake on acid excretion and renal glutamine metabolism was investigated and compared to the effects of NH4Cl-induced metabolic acidosis. Rats fed a diet containing 55% casein excreted more ammonia, phosphate, sulphate, and chloride than did rats fed a 13% casein diet, but, when they were given an 0.1 M NaHCO3 solution to drink, ammonia excretion was no longer elevated. Renal phosphate-dependent glutaminase and phosphoenolpyruvate carboxykinase activities, ammoniagenesis by isolated mitochondria, and the rate of renal gluconeogenesis were all elevated in the rats fed the high-protein diet but not if these rats also drank the sodium bicarbonate solution. Increased glutaminase and phosphoenolpyruvate carboxykinase activities, mitochondrial ammoniagenesis, and gluconeogenesis were all evident in rats made acidotic with NH4Cl. It is concluded that these metabolic adaptations evident in the kidneys of rats fed the high-protein diet are due to the acidogenic effects of increased protein intake.
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PMID:Renal glutamine metabolism in rats fed high-protein diets. 69 20

Phosphoenolpyruvate carboxylase from the Crassulacean plant Bryophyllum fedtschenkoi has been purified to homogenetity by DEAE-cellulose treatment, (NH4)2SO4 fractionation,, and chromatography on DEAE-cellulose and hydroxyapatite. Poly(ethylene glycol) is required in the extraction medium to obtain maximum enzyme activity. The purified enzyme has a specific activity of about 26 units/mg of protein at 25 degrees C. It gives a single band on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, corresponding to a mol.wt. of 105,000, and gives a single band on non-denaturing gel electrophoresis at pH8.4. Cross-linking studies at pH8.0 indicate that the subunit structure is tetrameric but that the dimer may also be an important unit of polymerization. Gel filtration results at pH6.7 confirm that the native enzyme is tetrameric with a concentration-dependent dissociation to a dimer. The kinetic behaviour is characterized by (i) relatively small variations in maximum velocity between pH5.5 and 9.0 with a double optimum, (ii) a reversible temperature-dependent inactivation between 30 and 45 degrees C, (iii) inhibition by malate, which is pH-sensitive, and (iv) almost Michaelis-Menten behaviour with phosphoenolpyruvate as the varied ligand but sigmoidal behaviour under suitable conditions with malate as the varied ligand. The findings are related to other studies to the possible role phosphoenolpyruvate carboxylase in controlling a circadian rhythm of CO2 fixation.
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PMID:Phosphoenolpyruvate carboxylase from the crassulacean plant Bryophyllum fedtschenkoi Hamet et Perrier. Purification, molecular and kinetic properties. 74 4

A translational assay was used to measure the level of mRNA coding for phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) in the rat kidney in various conditions in which the enzyme is induced. RNA extracted from whole kidneys was chromatographed on oligo(dT)-cellulose to select poly(A)-containing RNA. This crude mRNA preparation was able to stimulate amino acid incorporation into protein in a cell-free system containing an extract of wheat germ. Phosphoenolpyruvate carboxykinase could be detected among the polypeptides synthesized and quantitated by immunoprecipitation with a monospecific antibody followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amount of enzyme synthesized was proportional to the quantity of RNA added. The level of mRNA coding for phosphoenolpyruvate carboxykinase is increased 3-fold 6 h after triamcinolone injection. Translatable enzyme mRNA also increases 3-fold within 6 h of the onset of metabolic acidosis caused by an ammonium chloride load. In both cases, the increase in functional mRNA is commensurate with the stimulation of enzyme synthesis measured in vivo. Glucocorticoid administration and acidosis cause additive increases in the level of translatable phosphoenolpyruvate carboxykinase mRNA. The inductive effect of acidosis is preserved in the absence of the adrenals, hypophysis, thyroid, and parathyroids.
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PMID:Messenger RNA for renal phosphoenolpyruvate carboxykinase (GTP). Its translation in a heterologous cell-free system and its regulation by glucocorticoids and by changes in acid-base balance. 92 1

1. mRNA was extracted from the livers of starved rats and incubated in a heterologous cell-free protein-synthesizing system derived from rabbit reticulocytes. The presence of newly synthesized phosphoenolpyruvate carboxykinase (GTP) was detected by immunoprecipitation with a specific antibody to the enzyme and analysis by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. 2. The synthesis of the enzyme was dependent on the addition of rat liver RNA, whereas RNA isolated from rat spleen was inactive. If ovalbumin and anti-ovalbumin were used to form the immunoprecipitates, no radioactivity that migrated as phosphoenolpyruvate carboxykinase was detected. 3. The optimal concentrations of magnesium acetate and KCl for phosphoenolpyruvate carboxykinase synthesis were determined. 4. When polyribosomal RNA was separated by sucrose-gradient centrifugation, phosphoenolpyruvate carboxykinase mRNA migrated between 20 and 26 S in keeping with the high mol. wt. of the protein (85 000). 5. The presence of poly(A) in phosphoenolpyruvate carboxykinase mRNA was suggested by retention of mRNA activity on oligo(dT)-cellulose columns. 6. It was concluded that the cell-free synthesis of phosphoenolpyruvate carboxykinase can serve as a bioassay for intracellular phosphoenolpyruvate carboxykinase mRNA.
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PMID:Partial isolation and translation in vitro of messenger ribonucleic acid for phosphoenolpyruvate carboxykinase (guanosine triphosphate). 94 43

To determine the capacity of the chicken c-erbA (cTR-alpha) gene product in regulating expression of known thyroid hormone-responsive genes, both the cTR-alpha and the viral v-erbA genes were expressed in FAO cells, a rat hepatoma cell line defective for functional thyroid hormone receptors. Upon nuclear expression of the cTR-alpha protein the cells become responsive to thyroid hormone, as detected by expression of a number of genes (malic enzyme, phosphoenolpyruvate carboxykinase, and Na+/K(+)-ATPase) reported to be indirectly induced by the hormone in vivo. In addition, our data show that the c-erbA product directly activates the Moloney murine leukemia virus promoter in a ligand-dependent manner. The data show that the chicken c-erbA-alpha protein can modulate the expression of rat genes under either direct or indirect control by thyroid hormone.
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PMID:The chicken c-erbA alpha-product induces expression of thyroid hormone-responsive genes in 3,5,3'-triiodothyronine receptor-deficient rat hepatoma cells. 215 23

An active-site peptide from maize (Zea mays L.) phosphoenolpyruvate carboxylase has been isolated, sequenced and identified in the primary structure following chemical modification/inactivation of the enzyme by pyridoxal 5'-phosphate and reduction with sodium borohydride. The amino acid sequence of the purified dodecapeptide is Val-Gly-Tyr-Ser-Asp-Ser-Gly-L*ys-Asp-Ala-Gly-Arg, which corresponds exactly to residues 599-610 in the deduced primary sequence of the maize-leaf enzyme. Comparative analysis of the deduced amino acid sequences of the enzyme from Escherichia coli, Anacystis nidulans and C3, C4 and Crassulacean acid metabolism plants indicates that they all contain this specific lysyl group, as well as a high degree of sequence homology flanking this species-invariant residue. This observation suggests a critical role for Lys-606 during catalysis by maize phosphoenolpyruvate carboxylase. This represents the first identification of a specific, species-invariant active-site residue in the enzyme.
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PMID:Isolation and sequence of an active-site peptide from maize leaf phosphoenolpyruvate carboxylase inactivated by pyridoxal 5'-phosphate. 226 76

A primary rabbit kidney epithelial cell culture system has been developed which retains differentiated functions of the renal proximal tubule. In addition, the cells have a distinctive metabolism and spectrum of hormone responses. The primary cells were observed to retain in vitro a Na+-dependent sugar transport system (distinctive of the proximal segment of the nephron) and a Na+-dependent phosphate transport system. Both of these transport processes are localized on the apical membrane of proximal tubule cells in vivo. In addition, probenicid-sensitive p-aminohippurate (PAH) uptake was observed in basolateral membranes of the primary tubule cells, and the PAH uptake by these vesicles occurred at a rate that was very similar to that observed with membranes derived from the original tissue. Several other characteristics of the primary cells were examined, including hormone-sensitive cyclic AMP production and phosphoenolpyruvate carboxykinase (PEPCK) activity. Like the cells in vivo, the primary proximal tubule cells were observed to produce significant cyclic AMP in response to parathyroid hormone, but not in response to arginine vasopressin or salmon calcitonin. Significant PEPCK activity was observed in the particulate fraction derived from a homogenate of primary rabbit kidney proximal tubule cells.
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PMID:Primary rabbit kidney proximal tubule cell cultures maintain differentiated functions when cultured in a hormonally defined serum-free medium. 255 82


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