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)

The mannitol influence on mutagenesis of ionizing radiation and cyclophosphate has been studied in albino mongrel rats using the methods of genetic and biochemical analysis. N correlation is determined between antimutagenic action of this preparation and a decrease of malondialdehyde content in cells and free fractions of matrix lysosomes (beta-galactosidase; N-acetyl-beta-D-glucosaminidase) and firmly membrane-structurized microsomal (glucose-6-phosphatase) enzymes, whose level increases under the influence of mutagens. It is shown that, one of the way of antimutagenic actions of mannitol is connected with mutagenesis correction at the stage of origin of mutagenic products and their transport to chromosome DNA.
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PMID:[The interrelation of the antimutagenic action of mannitol to its effect on cellular metabolic processes]. 129 65

Controlled proteolytic digestion by trypsin or bacterial proteases limited to the cytosolic side of the native microsomal membrane is not efficient to inhibit glucose-6-phosphate hydrolysis. Modification of the microsomes with deoxycholate prior to protease treatment is prerequisite to allow accessibility of the integral protein and inhibition of enzyme activity. Glucose-6-phosphatase of native microsomes, however, is rapidly inactivated by micromolar concentrations of TPCK as well as TLCK. In deoxycholate-modified microsomes both reagents do not affect glucose-6-phosphate hydrolysis. These results indicate that in the native, intact microsomal membrane glucose-6-phosphatase is not accessible to proteolytic attack from the cytoplasmic surface. The putative inhibitory effect of some trypsin or bacterial protease preparations on glucose-6-phosphatase of native microsomes observed most possibly is a result of contaminating agents as TPCK or TLCK.
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PMID:Protease inhibitors but not proteases inhibit the glucose-6-phosphatase of native rat liver microsomes. 131 35

Liver cell functional heterogeneity has been shown to persist in toxic CCl4 cirrhosis in growing rats, but the zonation observed in cirrhotic nodules may be different in other types of cirrhosis. To investigate this possibility, we looked at the zonal activities of two microsomal enzymes, glucose-6-phosphatase and NADPH dehydrogenase, in cirrhotic nodules from growing rats with chronic cholestasis. Zonal activities were measured by quantitative cytochemistry and microdensitometry. Liver cell heterogeneity was demonstrated, and we confirmed that the metabolic zonation is the mirror image of that observed in toxic cirrhosis, with periportal activity at the nodule periphery and perivenular activity at the nodule centers. Glucose-6-phosphatase activity was 2.06 times higher at the peripheries of the nodules than at the centers, whereas NADPH dehydrogenase activity at the nodule periphery was 72% of the nodule center activity. We conclude that a liver cell functional heterogeneity persists in biliary rat cirrhosis, with zonation the reverse of that previously found in toxic CCl4 cirrhosis.
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PMID:Liver metabolic zonation in rat biliary cirrhosis: distribution is reverse of that in toxic cirrhosis. 131 72

Inflammation, induced by turpentine (0.1 ml i.m.), protected against carbon tetrachloride (CCl4)-induced hepatotoxicity based on serum activities of sorbitol dehydrogenase. Inflammation was confirmed by elevated serum ceruloplasmin activities, and was associated with high hepatic levels of metallothionein, a zinc protein proposed to protect against CCl4-induced injury. Inflammation suppressed cytochrome P-450 activities, but this was not associated with protection against CCl4-promoted liver microsomal injury as assessed by glucose-6-phosphatase activity loss. Thus, protection against plasma membrane injury did not result primarily from depressed microsomal activation of CCl4. Each effect of inflammation reported here resembled effects of zinc injections. This similarity strengthens the hypothesis that metallothionein protects against CCl4-induced hepatic plasma membrane injury.
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PMID:Inflammation, an inducer of metallothionein, inhibits carbon-tetrachloride-induced hepatotoxicity in rats. 131 82

We have utilized S-farnesyl-Leu-Ala-Arg-Tyr-Lys-Cys as a methyl-accepting substrate to characterize a membrane-bound C-terminal protein methyltransferase from rat liver. We have localized the activity to the microsomal fraction and show that the bulk of the enzyme fractionates by density gradient centrifugation with glucose-6-phosphatase, a marker of the endoplasmic reticulum, and not with 5'-nucleotidase, a marker of the plasma membrane, or galactosyl:N-acetylglucosamine transferase, a marker of the Golgi apparatus. This methyltransferase appears to form an integral part of the membrane structure. Its activity is markedly affected by a variety of detergents used to solubilize membrane proteins in their native form. All activity is lost when membranes are treated with seven different detergents at a concentration of 1% (w/v). The activity is inhibited by N-ethylmaleimide, although it can be protected against inactivation with its substrate S-adenosyl-L-methionine, or its product S-adenosyl-L-homocysteine. Finally, we find that 5'-methylthioadenosine, a substrate analogue reported to be an inhibitor of this activity in other studies, is not an effective inhibitor in vitro.
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PMID:Characterization of a rat liver protein carboxyl methyltransferase involved in the maturation of proteins with the -CXXX C-terminal sequence motif. 132 16

Glycogen storage diseases are usually identified in childhood. We present the clinical, biochemical and histological features of 10 patients first diagnosed in adult life. Five had glycogen storage disease type 1a, one type 1c, two type IX, and in two patients there were previously unreported abnormalities of hepatic glucose-6-phosphatase system activity. Of the latter, one patient had an inhibitor of liver glucose-6-phosphatase (pseudo-1b glycogen storage disease) the other having abnormal glucose-6-phosphatase activity and microsomal pyrophosphate transport. A glucagon test is suggested as a useful screening procedure. Glycogen storage disease should be considered in adults with symptoms suggesting hypoglycaemia.
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PMID:Glycogen storage disease diagnosed in adults. 132 55

Some of the acute actions of insulin may be mediated by an enzyme-modulating inositol phosphate glycan, produced by the insulin-sensitive hydrolysis of glycosyl-phosphatidylinositol (GPI) that is structurally similar to a membrane protein anchor. An inositol glycan fragment from the structurally characterized Trypanosoma brucei variant surface glycoprotein GPI anchor is evaluated for insulin-mimetic antilipolytic activity. The fragment specifically and dose-dependently inhibits isoproterenol-stimulated lipolysis. Like the effect of insulin, glycan-induced antilipolysis is blocked by the low Km cAMP phosphodiesterase inhibitor imazodan (CI-914) and the serine/threonine phosphatase inhibitor, okadaic acid, suggesting that the activation of both cAMP phosphodiesterase and serine/threonine protein phosphatases are necessary. Moreover, this fragment causes a specific and dose-dependent inhibition of both microsomal glucose-6-phosphatase (EC 3.1.3.9) and cytosolic fructose-1,6-bisphosphatase (EC 3.1.3.11) activity. Additionally, direct addition of the glycan to hepatocytes caused marked inhibition of glucose production from pyruvate. These results suggest that the direct modification of the activities of these two gluconeogenic enzymes by an inositol glycan may play a role in the inhibition of glucose output by insulin and provide the first evidence for the insulin-mimetic properties of a chemically characterized inositol glycan.
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PMID:An inositol phosphate glycan derived from a Trypanosoma brucei glycosyl-phosphatidylinositol mimics some of the metabolic actions of insulin. 132 96

The effect of amphotericin B on hepatic microsomal cytochrome P-450 (P-450) concentration was measured in vitro, in vivo and ex vivo in the rat. In vitro, both amphotericin B (0-500 micrograms/ml) and its vehicle, sodium deoxycholate (0-410 micrograms/ml), caused similar dose-dependent decreases of P-450 concentrations and glucose-6-phosphatase activity. Intravenous amphotericin B (3 mg/kg) given daily for 3 days decreased antipyrine clearance from control values of 1.24 +/- 0.24 ml/min to 0.67 +/- 0.12 ml/min (p less than 0.001); whereas antipyrine clearance was unchanged by sodium deoxycholate. The P-450 concentration on the third day was reduced from 0.74 +/- 0.14 nmol/mg protein in control rats to 0.33 +/- 0.09 nmol/mg protein in rats treated with amphotericin B (p less than 0.001). Sodium deoxycholate had no effect on P-450 concentration. In contrast, amphotericin B had no effect on either antipyrine clearance or P-450 concentration following enzyme induction by phenobarbital. Amphotericin B had no effect on microsomal glucose-6-phosphatase activity in vivo. Neither amphotericin B nor sodium deoxycholate induced lipid peroxidation, measured as malondialdehyde production. These results show that amphotericin B decreases hepatic cytochrome P-450 content and function in the rat. These effects can not be observed in the enzyme induced state. Amphotericin B has no effect on glucose-6-phosphatase in vivo, the key enzyme of the gluconeogenesis, indicating selective effects on hepatic microsomal function.
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PMID:Effect of amphotericin B on hepatic cytochrome P-450 and glucose-6-phosphatase in the rat. 132

The relationship between the neutral lipid and phospholipid metabolism and some structure-function peculiarities of regenerating rat liver endoplasmic reticulum membranes (13 hours after surgery, i.e., corresponding to the G1-period of the cell cycle) was studied. There was an increase in the degree of the endoplasmic reticulum membrane development and the nonesterified fatty acid (NFA) and triglyceride (TG) content in regenerating rat liver microsomes. The relative specific radioactivity of neutral lipid and phospholipid fractions in regenerating rat liver microsomes was lower than in control animals, presumably due to the high rate of the microsomal lipid exchange in the regenerating liver with other cell organelles. The changes in the lipid content and rate of their metabolism in the regenerating rat liver were associated with the increase in the membrane microviscosity and the decrease in the activity of the membrane-bound enzyme (glucose-6-phosphatase). The differences in the time-dependent changes in the synthesis and metabolism of lipids in the NFA and TG fractions may be regarded as an endogenous factor determining the structure-function peculiarities of endoplasmic reticulum membranes.
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PMID:[Lipid metabolism and structure-activity features of the endoplasmic reticulum membrane in regenerating rat liver]. 132 86

Three preterm infants born at 26-30 weeks' gestation who died between 103 and 266 days after birth were found to have elevated hepatic glycogen levels. Kinetic analysis of the hepatic microsomal glucose-6-phosphatase system demonstrated that one infant had abnormally low levels of activity of the glucose-6-phosphatase enzyme (partial type 1a glycogen storage disease) and two had deficiencies of T2, a microsomal phosphate/pyrophosphate transport protein (type 1c glycogen storage disease). In all three cases glycogen storage disease was not suspected prior to death even though both hypo- and hyperglycaemic episodes were recorded in the first 15 days after birth indicating that they had somewhat disordered blood glucose regulation. In the infant with low glucose-6-phosphatase enzyme activity, abnormal development of the glucose-6-phosphatase enzyme cannot be ruled out. This is the first description of abnormalities in the glucose-6-phosphatase system in preterm infants.
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PMID:Impairment of the activity of the hepatic microsomal glucose-6-phosphatase system in three preterm infants. 132 22


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