Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.9 (glucose-6-phosphatase)
 3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experiments were done on rats to investigate the nature of the renal response to metabolic acidosis and the changes in enzyme activity associated with increased ammoniagenesis. When metabolic acidosis was induced with oral feeding of ammonium chloride for 48 hr, there was an increase of activity of the enzyme phosphoenolpyruvate carboxykinase (PEPCK) in whole kidneys as well as in the kidney cortex. There was no change in PEPCK in liver, and glucose-6-phosphatase showed no change in kidney or liver in response to metabolic acidosis. The increase in PEPCK activity in kidney cortex varied with the degree of acidosis and there was a close correlation between cortical PEPCK activity and urinary ammonia. Kidney cortex mitochondrial PEPCK did not change in response to metabolic acidosis. An increase in PEPCK occurred as early as 6 hr after NH(4)Cl feeding, before there was any increase in kidney glutaminase I activity. Rats fed sodium phosphate, or given triamcinolone intramuscularly, developed a metabolic alkalosis, but there was increased urinary ammonia and an increase in activity of renal cortical PEPCK. Triamcinolone plus ammonium chloride induced a greater increase of PEPCK activity than triamcinolone by itself; on the contrary, the rise of glucose-6-phosphatase induced by triamcinolone was not enhanced by acidosis. Glucose-6-phosphatase from control and acidotic rats had identical kinetic characteristics. The results indicate that increased PEPCK activity is constantly related to increases of urinary ammonia. It is proposed that the increase of PEPCK activity is the key event in the ammoniagenesis and gluconeogenesis which follow on metabolic acidosis.
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PMID:Renal metabolic response to acid base changes. I. Enzymatic control of ammoniagenesis in the rat. 430 57

The kinetics of the induction of rat kidney phosphoenolpyruvate carboxykinase activity after triamcinolone and ammonium chloride administration have been investigated with a view to the further differentiation of the two processes. The half-life of kidney phosphoenolpyruvate carboxykinase activity, as measured from the decay curve after a single doses of triamcinolone, is approximately 1.4 hr. This compares with a half-life for the enzyme from acidotic kidney of approximately 3.4 hr. Analysis of the data indicates that the induction of phosphoenolpyruvate carboxykinase activity by triamcinolone may be attributed to an increase in de novo protein synthesis. Induction by acidosis is qualitatively distinct and is partly attributed to a reduction in the rate of decay of phosphoenolpyruvate carboxykinase activity. The activities of the gluconeogenic enzymes glucose-6-phosphatase, fructose-1,6-diphosphatase, and phosphoenolpyruvate carboxykinase in both liver and kidney have been measured in animals separately treated with triamcinolone and ammonium chloride. Triamcinolone significantly increases the activities of liver phosphoenolpyruvate carboxykinase, kidney glucose-6-phosphatase, and kidney phosphoenolpyruvate carboxykinase only; ammonium chloride stimulates a 200% increase in kidney phosphoenolpyruvate carboxykinase, but has no effect on the other enzymes. The induction processes whereby triamcinolone increases phosphoenolpyruvate carboxykinase activities in liver and kidney differ quantitatively.
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PMID:The effect of steroids and ammonium chloride acidosis on phosphoenolpyruvate carboxykinase in rat kidney cortex. II. The kinetics of enzyme induction. 434 28

We show that the production of glucose from glucose-6-phosphate hydrolysis outside microsomes is a function of glucose-6-phosphatase independent of its property to form glucose inside microsomes. Indeed, during development (before 1 day of age), mouse liver microsomes had glucose-6-phosphatase producing glucose solely outside microsomes. Furthermore, in vivo treatment of rats with the glucocorticoid analogue triamcinolone resulted in increased glucose-6-phosphatase activity outside but not inside microsomes and without change in the catalytic subunit 40 kDa glucose-6-phosphatase mRNA abundance or protein level, indicating that other factors induced by triamcinolone (e.g., altered membrane lipid environment and/or a regulatory protein) were responsible for the activity change. Triamcinolone treatment also lessened the inhibition of glucose-6-phosphatase by pyridoxal 5'-phosphate (PLP), but this effect was not due to an interaction of PLP with the active site. Accordingly, reversal of the inhibition was observed after permeabilization of the microsomes. The two distinct orientations of liver microsomal glucose-6-phosphate phosphohydrolase suggest different physiological roles played by this enzyme in the endoplasmic reticulum membrane.
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PMID:Evidence that the transit of glucose into liver microsomes is not required for functional glucose-6-phosphatase. 924 38