Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phospholipase A2 (PLA2) treatment has been shown previously to stimulate the sodium-dependent high-affinity choline uptake system as assessed by both the specific binding of [3H]hemicholinium-3 ([ 3H]HCh-3) and the uptake of [3H]choline. In the present study, the specificity of PLA2-induced stimulation upon [3H]HCh-3 binding has been examined. PLA2, as well as phospholipase C (PLC), treatment of synaptic membranes produced a dose-dependent increase in the specific binding of [3H]HCh-3 whereas neither phospholipase B nor phospholipase D had any effect. PLC-induced stimulation of [3H]HCh-3 binding resulted from a significant decrease in the Kd without a change in the maximum binding of [3H]HCh-3 binding. PLC treatment of synaptosomes resulted in an inhibition of [3H]choline uptake accompanied by an inhibition of Na+, K+-adenosine triphosphatase activity. In contrast to the increase of [3H]HCh-3 binding, the specific binding of both [3H]desipramine and [3H]mazindol was decreased by PLA2 treatment. After PLA2 treatment, [3H]HCh-3 binding was increased about 2.5-fold over basal levels in different regions of the brain. Electrolytic lesions of the medial septal nucleus and kainic acid-induced lesions of the striatum resulted in a marked reduction of [3H]HCh-3 binding in the hippocampus and the striatum, respectively. Residual [3H]HCh-3 binding in the denervated hippocampus and lesioned striatum was increased by PLA2 treatment but remained lower than that in PLA2-treated controls. Finally, atropine-induced up-regulation of [3H]HCh-3 binding in vivo was not additive with PLA2-induced stimulation. These results support the hypothesis that PLA2 might be involved in the regulation of the sodium-dependent high-affinity choline uptake.
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PMID:Specificity of the activation of [3H]hemicholinium-3 binding by phospholipase A2. 273 47

Daily, oral administration of chlorphentermine (60 mg/kg) for 5 days to rats produced a significant increase in the concentration of whole lung total phospholipid as well as sphingomyelin, phosphatidylserine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, and phosphatidylcholine. Similarly, a significant elevation in total and all individual phospholipid components was found in the lysosomal fraction of chlorphentermine-treated rat lung. In contrast, the activities of pulmonary Na+,K+-ATPase and alkaline phosphatase, enzymatic markers of membrane function, were not markedly affected by chlorphentermine treatment. The observed lung phospholipidosis was accompanied by inhibition of phospholipase C activity. Regardless of the phospholipid substrate, chlorphentermine significantly decreased pulmonary phospholipase C to approximately the same extent. Our data show that accumulation of phospholipid in whole lung and lysosomes is associated with an inhibition of phospholipase C activity.
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PMID:Role of phospholipase C in chlorphentermine-induced pulmonary phospholipidosis in rat. 283 77

We investigated the effects of phospholipases on the activity of microsomal Cl-ATPase in the rat brain, in reference to those on the activities of Na,K-ATPase and anion-insensitive Mg-ATPase. In the presence of phospholipase A2 or phospholipase C, which almost completely hydrolyzed microsomal phosphoglycerides, the activities of Cl-ATPase and Na,K-ATPase were decreased to 8-50% of the control, but anion-insensitive Mg-ATPase activity was not altered. On the other hand, with sphingomyelinase treatment, only anion-insensitive Mg-ATPase was slightly inactivated. On the addition of phospholipids (phosphatidylserine (PS), phosphatidylinositol (PI) and microsomal phospholipid mixture), Cl-ATPase activity slightly recovered only with PI, while Na,K-ATPase activity partially recovered with either phospholipid. These data suggest that Cl-ATPase requires intact membrane lipid conformation and especially PI for its maximal activity.
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PMID:Effects of phospholipases on Cl-ATPase in the rat brain. 284 74

A metal ion-activated acid ATPase was present in chicken liver lysosomes. We used Zn2+ as an activator. Lysosomal extract containing octylglucoside from chicken liver was centrifuged at 100,000 xg for 60 min. The supernatant was analyzed by gel filtration on a Sepharose 6B column. Two peaks of metal ion-activated acid ATPase activities were obtained according to the distribution patterns. Each of the two active fractions was incubated with phosphatidylinositol-specific phospholipase C at 37 degrees C for 60 min. The resulting solution was analyzed by gel filtration on a smaller size column of Sepharose 6B again. Molecular weight of the major peak was altered from approx. 1,600,000 to 130,000, whereas that of the minor one, 700,000, remained unchanged.
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PMID:Acid ATPase from chicken liver lysosomes. III. A metal ion-activated ATPase combines with membranous phosphatidylinositol. 294 83

Alkaline phosphatase was released from protoplasts of the yeast Saccharomyces cerevisiae without cell lysis not only by phosphatidylinositol (PI)-specific phospholipase C but also by phosphatidylcholine (PC)-hydrolyzing phospholipase C. Activities of mitochondrial enzymes such as succinate dehydrogenase, antimycin-sensitive NADH-cytochrome c reductase, and oligomycin-sensitive ATPase were decreased by the action of PC-hydrolyzing phospholipase C. Hydrolysis of microsomal PC or PI did not cause any decrease in the activities of NADPH-cytochrome c reductase and antimycin-insensitive NADPH-cytochrome c reductase. In the requirement of phospholipids, the properties of yeast mitochondrial enzymes were very close to those of mammalian mitochondrial enzymes, whereas those of yeast microsomal enzymes were completely different from those of mammalian microsomal enzymes.
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PMID:Effects of phospholipases C on membrane-bound enzymes of yeast. 296 99

The effect of phospholipase C on two isozymes (alpha (+) and alpha forms) of rat brain (Na+ + K+)-ATPase and the temperature-dependence of their activities were investigated. Phospholipase C from Clostridium welchii inhibited the activities of the enzymes treated with and without pyrithiamin or N-ethylmaleimide, a preferential inhibitor of the alpha (+) form, but the extent of the inhibition was higher in the control enzyme than in the treated enzymes. The treatment of the (Na+ + K+)-ATPase with phospholipase C altered a ratio between high- and low-affinity components for ouabain inhibition. It also caused the similar change in a ratio between the alpha (+) and alpha forms of Na+-stimulated phosphorylation from [gamma-32P]ATP. These findings indicate that the alpha (+) form of rat brain (Na+ + K+)-ATPase is more sensitive to phospholipase C than the alpha form. Analysis of Arrhenius plots of the activities of the control and pyrithiamin-treated enzymes showed that there was a difference between the two enzymes in a break point. We suggest that two isozymes of rat brain (Na+ + K+)-ATPase differ in the interaction with phospholipids or in the lipid-environment.
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PMID:Difference in phospholipid dependence between two isozymes of brain (Na+ + K+)-ATPase. 301 25

Ouabain-sensitive 86Rb+ uptake by isolated rat hepatocytes was studied to elucidate how Ca2+-mobilizing hormones stimulate the Na+-pump. Stimulation of this uptake was observed with concentrations of vasopressin ([8-arginine]vasopressin, AVP), angiotensin II, and norepinephrine which elicited Ca2+ mobilization and phosphorylase activation. These results suggested that changes in cytosolic Ca2+, mediated by inositol trisphosphate, might trigger sodium pump stimulation by AVP. However, in hepatocytes incubated in Ca2+-free Krebs-Henseleit buffer, Na+-pump activity was not altered over 15 min by either 1.5 mM EGTA or 1.5 mM Ca2+. Furthermore, incubation of cells in 5 mM EGTA for 15-30 min drastically impaired the ability of AVP to increase cytosolic Ca2+, but only modestly attenuated AVP-stimulated Na+-pump activity. Two tumor promoters, phorbol myristate acetate (PMA) and mezerein, stimulated Na+/K+-ATPase-mediated transport activity. Similarly, addition of synthetic diacylglycerols or of exogenous phospholipase C from Clostridium perfringens to increase endogenous diacylglycerol levels also resulted in a stimulation of the Na+-pump in the absence of changes in cytosolic or total cellular Ca2+ levels. Stimulation of the Na+-pump by the combination of maximal concentrations of PMA and AVP did not produce an additive response, and both agents displayed a transient time course, suggesting that the two agents share a common mechanism. Stimulation of the Na+-pump by AVP and PMA was not blocked by amiloride analogs which inhibit Na+/H+ exchange, but these compounds blocked the action of insulin. These data suggest that the elevated Na+/K+-ATPase-mediated transport activity observed in hepatocytes following exposure to Ca2+-mobilizing hormones is a consequence of stimulated diacylglycerol formation and may involve protein kinase C.
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PMID:The hormone-sensitive hepatic Na+-pump. Evidence for regulation by diacylglycerol and tumor promoters. 302 43

Ouabain and related cardiac glycosides stimulate phospholipase C activity 5-fold in rat pinealocytes. The combined treatment of ouabain and norepinephrine, which also stimulates phospholipase C, produces an additive effect. The effects of either ouabain or norepinephrine are blocked by EGTA. However, there are notable differences. The stimulatory effect of ouabain is lost when extracellular Na+ is reduced to 20 mM and is not blocked by prazosin. In contrast, the stimulatory effect of norepinephrine is not blocked when extracellular Na+ is reduced to 20 mM but is blocked by prazosin. Ouabain appears to increase phospholipase C activity through a mechanism involving inhibition of Na+,K+-ATPase, and an accumulation of intracellular Na+ and Ca2+, not involving alpha 1-adrenoceptors. These findings raise the possibility that activation of phospholipase C might be a more general effect of cardiac glycosides.
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PMID:Cardiac glycosides stimulate phospholipase C activity in rat pinealocytes. 303 Mar 2

The main electric organ of Electrophorus electricus is particularly rich in thiamine triphosphate, which represents 87% of the total thiamine content in this tissue. The thiamine pyrophosphate concentration, however, is very low in the eel electric organ and skeletal muscle as compared with other eel or rat tissues. Furthermore, electroplax membranes contain a whole set of enzymes responsible for the dephosphorylation of thiamine tri-, pyro- and monophosphate. Thiamine triphosphatase has a pH optimum of 6.8 and is dependent on Mg2+. The real substrate of the enzyme is probably a 1:1 complex of Mg2+ and thiamine triphosphate. Thiamine pyrophosphatase is activated by Ca2+. The apparent Km for thiamine triphosphate and Vmax are found to be, respectively, 1.76 mM and 5.95 nmol/mg of protein/min. Thiamine triphosphatase activity is inhibited at physiological K+ concentrations (up to 90 mM) and increasing Na+ concentrations (50% inhibition at 300 mM). ZnCl2 (10 mM) inhibits 90% of the enzyme activity. ATP and ITP are also strongly inhibitory. No significant effect of neurotoxins is seen. Membrane-associated thiamine triphosphatase is affected differently by proteolytic enzymes and is partially inactivated by pretreatment with phospholipase C and neuraminidase. The physiological significance of thiamine triphosphatase is discussed in relation to a specific role of thiamine in the nervous system.
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PMID:Thiamine triphosphate and membrane-associated thiamine phosphatases in the electric organ of Electrophorus electricus. 303 30

Mammalian cells treated with low concentrations of phospholipase C become permeable to the protein toxin alpha-sarcin. A similar permeabilization is not induced upon treatment with other lipases such as phospholipase A2, sphingomyelinase, or cholesterol esterase. Concentrations of 10 micrograms/ml alpha-sarcin almost completely blocked translation in HeLa cells treated with 0.3 U/ml phospholipase C (PL-C) for 1 h. In contrast, 200 micrograms/ml of alpha-sarcin had no effect at all on protein synthesis in untreated cells. Other macromolecules such as horseradish peroxidase and luciferase also enter into cells if they are treated with phospholipase C. This permeabilization method is fully reversible. As soon as 5 min after PL-C removal, the cells become impermeable to alpha-sarcin. Other metabolites such as uridine nucleotides are partially released after PL-C incubation, whereas the content of 86Rb+ remains at control levels, probably because the Na+/K+ ATPase activity increases.
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PMID:Exogenous phospholipase C permeabilizes mammalian cells to proteins. 313 47


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