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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 protective action of aspartic acid on isolated and perfused rat liver was studied. In case of D-galactosamine intoxication the GOT, GPT and SDH activity and the lactate and pyruvate concentration in the perfusion medium were less augmented and the glycogen level in hepatic tissue was less diminished in animals treated with aspartic acid, as compared to controls. The histochemical applied (PAS reaction for glycogen, nucleic acids, NADH2-diaphorase, glucose-6-phosphatase and membrane-ATP-ase), also stated a protecting effect in the treated animals. The protective action of aspartate is hypothetically considered to be exerted by its capacity to reestablish the cellular deficit of pyridine nucleotides and thus to improve the synthesis of nucleic acids, glycoprotein and glycolipids or/and by its participation in various metabolic pathways.
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PMID:Protecting action of aspartate on the hepatic changes induced by D-galactosamine. 18 87

A Golgi-rich fraction is prepared from cat hepatocytes by the means of a four-step sucrose density gradient. The material applied to this gradient is composed either of smooth microsomes prepared from healthy animals, or of total microsomes prepared from cat treated by 50 per cent ethanol (0.6 g/100 g body weight, administered by stomach tube). A light fraction (d : 1.10) is obtained by the two procedures. It does not show any glucose-6-phosphatase activity, but is enriched in sialyltransferase, known as a marker enzyme for Golgi apparatus. It also contains the three enzymes implicated in the biosynthetic pathway for UDP-glucose (glucokinase, phosphoglucomutase and UTP : glucose-1-phosphate uridylyltransferase). UDP-glucose being the ultimate substrate in membranous glucosylation reactions, these results could support the hypothesis that sugar-nucleotides necessary for the glycoprotein biosynthesis are produced in the Golgi vesicles directly.
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PMID:[Presence of enzymes catalyzing UDP-glucose biosynthesis in a low density Golgi fractions of cat hepatocytes]. 22 65

Cytochemical studies on uninseminated mature eggs of Limulus demonstrate the presence of carbohydrates, lipids and proteins in the egg envelopes and yolk. The vitelline envelope, cortical region and yolk are rich in 1,2-glycols, with the vitelline envelope, containing fewer reactive 1,2-glycol groups than other components of the egg. Neutral mucopolysaccharides are found in the cortical region and yolk, but only the cortical region of the eggs demonstrate the presence of sulfated mucosubstances (which are in part glycoprotein in nature) and glucose-6-phosphatase. Protein is evident in all egg components. Biochemical analysis demonstrate the protein in the egg envelopes of uninseminated eggs is composed of sixteen amino acids while that of developing eggs contain seventeen amino acid residues. Electrovalent linkages and non-S-S- covalent linkages between protein chains are shown to be instrumental in maintaining the stuctural integrity of Limulus egg envelopes. Neutral lipids, unsaturated lipids, phospholipids and fatty acids are demonstrated in yolk bodies and lipoproteins, unsaturated lipids and fatty acids constitute part of the egg envelopes. DNA is concentrated in the cortical region and the yolk bodies
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PMID:The cytochemistry of Limulus eggs. 45 98

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

Antibodies raised against purified components of glucose-6-phosphatase were used to study the transmembrane orientation of the complex. Measurements of glucose-6-phosphatase activities and immunoblot analysis of sealed microsomes and detergent-solubilized microsomes after treatment with proteases suggested that most of the catalytic subunit resides within the lumen of the endoplasmic reticulum. In contrast, other components of glucose-6-phosphatase are accessible to the cytoplasm. Treatment of the partially purified glucose-6-phosphatase enzyme with glycopeptide N-glycosidase indicated that the catalytic subunit of the enzyme was a glycoprotein.
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PMID:Transverse topology of glucose-6-phosphatase in rat hepatic endoplasmic reticulum. 185 Feb 36

Envelopment of herpes simplex virus type-1 (HSV-1) was investigated in relation to membrane differentiation in dissociated anterior pituitary cells. The number of cells stained positively with anti-HSV-1 serum was increased from 16 h to 31 h post infection. During this period, electron microscopy revealed that a number of nucleocapsids (unenveloped particles) were accumulated in the Golgi area, where they frequently became surrounded by a double membrane of short Golgi cisternae or by one with a Golgi associated endoplasmic reticulum lysosome (GERL)-like structure. The inner membrane of the cisterna surrounding the nucleocapsids showed regional specialization which was characterized by increased thickness and electron opacity. Acid phosphatase activity, a marker for GERL or trans Golgi cisternae, appeared in the cytoplasmic short cisternae surrounding the nucleocapsids, whereas glucose-6-phosphatase activity, a marker for the nuclear envelope or for endoplasmic reticulum, was not demonstrated in such cisternae. Monoclonal antibody against glycoprotein gD revealed that gD was localized in the trans Golgi membrane as well as in the envelope of the virion. The antibody-binding sites were highly concentrated in the area where Golgi membranes showed increased opacity. Furthermore, nucleocapsids were surrounded exclusively by gD-positive cisternal (Golgi or Golgi-derived) membranes. Thus, our results indicate that the envelope of HSV is derived from trans Golgi cisterna (GERL), and that some viral components, including gD, destined for the envelope may be assembled initially in the Golgi membrane, which is thereby transformed into the envelope of the virus.
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PMID:Transformation of Golgi membrane into the envelope of herpes simplex virus in rat anterior pituitary cells. 256 Jul 16

Post-mortem brain samples from patients with either Huntington's disease, Alzheimer-type dementia or appropriate controls were assayed for endoplasmic reticulum enzymes, NADPH-cytochrome c reductase, neutral alpha-glucosidase, inosine diphosphatase, alpha-mannosidase and glucose-6-phosphatase and for Golgi enzymes, fucosyl- and galactosyl-transferases. In Alzheimer-type dementia there was a selective decrease in alpha-glucosidase activity in the temporal cortex. In Huntington's disease there was a selective decrease of putamen alpha-glucosidase and fucosyl-transferase activities. It is suggested that these changes reflect highly specific alterations in glycoprotein synthesis and processing and may contribute to the underlying pathology of these disorders.
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PMID:Loss of endoplasmic reticulum-associated enzymes in affected brain regions in Huntington's disease and Alzheimer-type dementia. 293 94

From the histochemical investigation carried out on the digestive tract of rats after 7 days space flight in the soviet biosatellite Cosmos 1667 it resulted that neutral and acid glycoproteins diminished slightly in the sublingual gland, stomach, small intestine and the colon. Some intestinal enzymes augmented (leucineaminopeptidase, acid phosphatase, adenosinetriphosphatase and glucose-6-phosphatase). The changes observed after this flight were less marked than after an 18 day flight (in the Soviet biosatellite Cosmos 936 and 1129) and similar to those revealed after 7 days of hypokinesia. The glycoprotein changes were close to those observed after a 5-day flight (Cosmos 1514) but in which there were pregnant rats; after these last flights, the enzymes were not studied.
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PMID:The digestive tract of rat after flight in the biosatellite Cosmos 1667. 311 67

A membrane vesicle fraction isolated from exponentially growing Aspergillus fumigatus strain Ag 507 cultures was obtained by mechanical disruption of intact Aspergillus cells under specific osmotic conditions followed by a pH fractionation technique. Electron micrographs of the membrane vesicles indicated unit membrane structures free from cell wall material. High glucose-6-phosphatase and low lactate dehydrogenase activities verified the relative purity of the membrane vesicle fraction. Allergic bronchopulmonary aspergillosis (ABPA) patient and normal human sera were incubated with the membrane vesicle fraction followed by colloidal gold tagged rabbit antiserum to human IgG or IgE. Electron micrographs indicated ABPA patient sera possessed specific IgG and IgE antibodies to membranous components. The detergent octyl-beta-D-glucopyranoside was used to extract membrane vesicle components (MC). The enzyme profile of MC compared with cell sap components (CS) showed differences in types of enzymes. Two-dimensional polyacrylamide gel electrophoretic analyses of MC and CS detected components shared as well as unique to each fraction. In crossed immunoelectrophoresis using both rabbit antisera raised to MC and ABPA patient sera, 5 peaks were detected, while analysis of CS using rabbit antisera raised to CS produced 20 major peaks. Immunoelectrophoresis and double immunodiffusion data supported the crossed immunoelectrophoretic data: MC differed from CS. Enzyme-linked immunosorbent assay indicated high specific IgG and IgE antibody levels to MC in ABPA patient sera. Crossed immuno-affinoelectrophoresis with concanavalin A partially characterized the MC, which consist of components which have glycoprotein elements (i.e., containing alpha-D-glucose or alpha-D-mannose).
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PMID:Biochemical and immunochemical analyses of detergent solubilized antigens from membrane vesicles of Aspergillus fumigatus. 332 2

Severe hepatic damage with submassive necrosis induced in rats by an intraperitoneal injection of a single dose of galactosamine hydrochloride was studied. In the severely damaged liver, the remarkable decreases of glycogen and UDPG in the damaged liver were seen. This means extreme decrease in the reserve power of glycolysis. Moreover, the activities of glucose-6-phosphatase and fructose-1,6-diphosphatase decreased. Therefore, the glucose release from liver into the blood stream decreases and the inhibition of gluconeogenesis occurs. In the damaged liver, the decrease of UTP which is essential for the synthesis of sugar moiety of polysaccharide, was seen. Further, the activities of L-glutamine: D-fructose-6-phosphate amidotransferase and UDP N-acetylglucosamine 2'-epimerase which are two key enzymes of polysaccharide synthesizing enzyme were seen to decrease remarkably. In the damaged liver, the glycoprotein fraction decreased more strikingly than the acid mucopolysaccharide fraction. Moreover, the decrease of fructose-1,6-diphosphatase activity seems also to effect on the inhibition of polysaccharide synthesis. In these respects, in the severe hepatic damage, the synthesis of glycoprotein which is essential for liver cell seems to be inhibited.
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PMID:Studies on severe hepatic damage induced by galactosamine. 617 14


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