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:4.6.1.1 (adenylate cyclase)
19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

D-Lysergic acid diethylamide and D-2-bromolysergic acid diethylamide are competitive antagonists of the histamine activation of adenylate cyclase [ATP pyrophosphate-lyase (cyclizing); E.C. 4.6.1.1] in broken cell preparations of the hippocampus and cortex of guinea pig brain. The adenylate cyclase is linked to the histamine H2-receptor. Both D-lysergic acid diethylamide and D-2-bromolysergic acid diethylamide show topological congruency with potent H2-antagonists. D-2-Bromolysergic acid diethylamide is 10 times more potent as an H2-antagonist than cimetidine, which has been the most potent H2-antagonist reported, and D-lysergic acid diethylamide is about equipotent to cimetidine. Blockade of H2-receptors could contribute to the behavioral effects of D-2-bromolysergic acid diethylamide and D-lysergic acid diethylamide.
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PMID:Antagonism of histamine-activated adenylate cyclase in brain by D-lysergic acid diethylamide. 2 36

The properties of digitonin-solubilized beta-adrenergic receptors from frog erythrocyte membranes were studied by gel exclusion chromatography on AcA 34 Ultragel. beta-Adrenergic receptor binding activity in these membranes can be identified by both an agonist ligand, [(3)H]hydroxybenzylisoproterenol, and the antagonist ligands, [(3)H]dihydroalprenolol and (125)I-labeled hydroxybenzylpindolol. Occupancy of the beta-adrenergic receptors with the [(3)H]hydroxybenzylisoproterenol agonist prior to their solubilization from the membrane leads to an increase in apparent receptor size. Alterations in the molecular size of the receptor cannot be mimicked by occupancy of the binding site with the antagonist ligands. Exposure of frog erythrocyte membranes to [(3)H]hydroxybenzylisoproterenol agonist in the presence of 10 muM Gpp(NH)(p), a guanyl nucleotide analog that exerts multiple regulatory effects on the catecholamine-sensitive adenylate cyclase [ATP pyrophosphate-lyase (cyclizing); EC 4.6.1.1] system, results in the elution of the [(3)H]hydroxybenzylisoproterenol radioligand in both the region characteristic of the agonist-receptor complex and the region characteristic of the antagonist-receptor complex. The precise molecular interactions responsible for the agonist-induced increase in apparent beta-adrenergic receptor size are still unresolved. However, the low concentrations of agonist that are capable of altering apparent receptor size and the sensitivity of this effect to guanyl nucleotides suggest that these phenomena may be intimately involved in eliciting the physiological effects of beta-adrenergic catecholamines at the molecular level.
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PMID:Agonist-induced increase in apparent beta-adrenergic receptor size. 2 13

The beta-adrenergic agonist L-isoproterenol stimulated the enzymic synthesis of phosphatidyl-N-monomethylethanolamine and phosphatidylcholine in rat reticulocyte ghosts containing the methyl donor S-adenosyl-L-methionine. The stimulation was stereospecific, dose-dependent, and inhibited by the beta-adrenergic agonist propranolol. The addition of GTP inside the resealed ghosts shifted the dose-response of phospholipid methylation by L-isoproterenol to the left by 2 orders of magnitude. Direct stimulation of adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] with sodium fluoride or cholera toxin did not increase the methylation of phospholipids. At a concentration of S-adenosyl-L-methionine that stimulates synthesis of phosphatidyl-N-monomethylethanolamine, the activity of isoproterenol-sensitive adenylate cyclase was increased 2-fold without changes in the basal activity of adenylate cyclase and the number of beta-adrenergic receptors. The increase of phospholipid methylation by L-isoproterenol decreased membrane viscosity and increased translocation of methylated lipids. These findings indicate that enhancement of phospholipid methylation by L-isoproterenol decreases membrane microviscosity and thus increases lateral movement of the beta-adrenergic receptors and coupling with adenylate cyclase.
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PMID:beta-Adrenergic receptor agonists increase phospholipid methylation, membrane fluidity, and beta-adrenergic receptor-adenylate cyclase coupling. 3 51

Adenyl cyclase activity in normal human epidermis was detected by an electron microscopic cytochemical technique. The sodium fluoride sensitive receptors were demonstrated on the outer sheath of the cell membranes. Adenyl cyclase activity was demonstrated in the basal cells and in the 4-5 lower layers of the Malpighian cells, while the superficial layers, stratum granulosum and stratum corneum showed no activity. The findings confirm and extend previous biochemical studies and provide a clue to the conception of the adenyl cyclase enzyme as a transmembrane arranged system.
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PMID:Electron microscopic cytochemistry for demonstration of sodium fluoride sensitive adenyl cyclase in normal human epidermis. 7 62

Following the initiation of development, amoebae of Dictyostelium discoideum aggregate chemotactically toward cyclic AMP (cAMP). Adenyl cyclase, cAMP phosphodiesterase, and cAMP binding sites all increase 20--40 fold during the first few hours of development. It has been shown that addition of 1 mM EDTA and 5 mM MgCl2 accelerates the aggregation process. Likewise, the calcium ionophore, A23187, leads to precocious aggregation while 4 X 10(-5) M progesterone considerably delays it. These treatments have now been shown to result in increased accumulation of adenyl cyclase in the case of EDTA and Mg2+ or the ionophore and greatly decreased accumulation in the case of the steroid. Treatment with EDTA and Mg2+ or the ionophore has been shown not only to accelerate aggregation in wild-type amoebae but to overcome complete blocks to aggregation in certain mutant strains. We have found that addition of Mn2+ will also permit aggregation of mutant cells otherwise unable to aggregate. This divalent ion, unlike EDTA and Mg2+ or the ionophore, was shown to directly stimulate adenyl cyclase. Calcium ions were also found to affect the enzyme such that at Ca2+ concentrations found within the cells the great majority of the activity is inhibited. Manganese ions can overcome the inhibition by Ca2+. These findings show that conditions which stimulate aggregation result in increased activity of adenyl cyclase either by increased accumulation of the enzyme or by increased activity of the available enzyme, and support the proposed central role of adenyl cyclase in aggregation.
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PMID:The effect of divalent cations on aggregation of Dictyostelium discoideum. 10 68

Sugars such as glucose are transported into Escherichia coli by a coupled phosphorylation mechanism (the phosphoenolpyruvate:sugar phosphotransferase system, PTS). Transport of sugars through the PTS results in inhibition of adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] activity by a mechanism involving a change in the state of phosphorylation of PTS proteins. Other sugars (e.g., lactose) are transported without modification by a mechanism involving proton cotransport, which requires a proton motive force across the cell membrane. We show here that uptake of sugars through the lactose transport system results in inhibition of adenylate cyclase activity if the proton symport mechanism is also active. The protonophore carbonyl cyanide m-chlorophenylhydrazone also inhibits adenylate cyclase activity. These data suggest that the steady-state electrochemical proton gradient regulates the activity of adenylate cyclase. We propose that sugar-dependent inhibition of adenylate cyclase activity may occur by either of two mechanisms. Sugars transported by the PTS inhibited adenylate cyclase activity by dephosphorylation of a regulatory protein, while sugars transported by the proton motive force system inhibit adenylate cyclase activity as a result of collapse of the proton electrochemical gradient.
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PMID:Escherichia coli adenylate cyclase complex: regulation by the proton electrochemical gradient. 10 76

Total and specific activity of cardiac NaK-ATPase (EC 3.6.1.3) in the rat varied parallel with the thyroid state. The functional state of the thyroid altered the number of NaK-ATPase molecules in the cell; the catalytic activity (turnover number) of individual enzyme molecules did not change. Sensitivity of NaK-ATPase to its specific inhibitor, ouabain, (as estimated from the half-maximal inhibitory concentration of ouabain) was lower in hypothyroidism but remained unchanged in hyperthyroidism relative to the euthyroid state. Action of thyroid hormones appeared to be selective for NaK-ATPase as shown by the behavior of another enzyme of the sarcolemma, adenyl cyclase. Adenyl cyclase of the heart was not affected by hyperthyroidism but was significantly elevated in hypothyroidism relative to euthyroid controls.
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PMID:Alterations of cardiac NaK-ATPase by the thyroid state in the rat. 14 50

Genetically obese (ob/ob) mice, mice that became obese after treatment with gold thioglucose, and lean animals were studied in the euthyroid state, after induction of hypothyroidism, and after treatment with triiodothyronine. The activity of glycerol 3-phosphate dehydrogenase (sn-glycerol-3-phosphate:(acceptor) oxidoreductase; EC 1.1.99.5] was reduced in the livers from hypothyroid animals and was increased by treatment with triiodothyronine in all groups. The activity of the ouabain-suppressible sodium- and potassium-dependent ATPase (ATP phosphohydrolase; EC 3.6.1.3) was increased by triiodothyronine and reduced by hypothyroidism in the lean and gold thioglucose-treated obese animals. In the obese (ob/ob) mice, on the other hand, treatment with triiodothyronine did not increase the activity of this enzyme, which remained at the level found in hypothyroid animals. This enzymatic activity was reduced in both liver and kidney. Adenylate cyclase [ATP pyrophosphate-lyase (cyclizing); EC 4.6.1.1] activity in liver membranes, however, was similar in all three groups of mice. This enzyme complex was activated by glucagon and was unaffected by treatment with thyroid hormones. The lack of a thyroid-dependent ouabain-suppressible (Na(+) + K(+))-ATPase in the tissues of the obese (ob/ob) mouse could explain most, if not all, of the abnormalities that have been described in this animal.
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PMID:An enzymatic defect in the obese (ob/ob) mouse: loss of thyroid-induced sodium- and potassium-dependent adenosinetriphosphatase. 14 80

NAD is a necessary cofactor for the activation of adenylate cyclase (ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1) by cholera toxin. Lysates of certain types of cell that hydrolyze their endogenous store of NAD after cell disruption respond poorly or not at all to cholera toxin. Lysates of pigeon erythrocytes, which lack enzymes that degrade NAD, provide a convenient and reproducible system for assaying the activity of cholera toxin in vitro and allow investigation of the mechanism of action of the toxin upon broken cells.
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PMID:Involvement of nicotinamide adenine dinucleotide in the action of cholera toxin in vitro. 16 78

Simple one step assay methods for adenylate cyclase (ATP pyrophosphate-lyase (cyclizing) EC 4.6.1.1) and cyclic nucleotide phosphodiesterases (3',5'-cyclic nucleotide 5'-nucleotidohydrolase EC 3.1.4.17) have been developed. [alpha-32-P] ATP is used as the substrate for adenylate cyclase. Acid-heat destruction of [32-P] ATP remaining after the cyclase reaction followed by Zn-Ba treatment quantitatively leaves cyclic [32-P] AMP in the supernatant essentially free from other 32-P-containing compounds. This assay method requires no corrections for recovery and routinely yields blank values less than 0.03 per cent. If higher sensitivity is desired, a simple 5 min alumina column step can be introduced into the procedure which quantitatively elutes cyclic [32-P] AMP directly into a liquid scintillation vial and lowers the blank values to less than 0.002 per cent. This method is rapid and easily performed, without sacrificing high reliability, specificity, or sensitivity. One step phosphodiesterase assays are easily accomplished using 32-P-labeled cyclic nucleotides as substrates. Descending paper chromatography of the reaction mixture on individual 2 cm wide paper strips gives a complete and quantitative separation of all possible products including [5'-32-P] AMP and [5'-32-P] GMP from their respective 32-P-labeled 3',5'-cyclic nucleotides in 1-2 h. The paper strips are cut, inserted in scintillation vials without scintillant and the 32-P-products determined by Cerenkov counting. Low blank values of less than 0.5 per cent and the use of high specific activity 32-P-labeled cyclic nucleotide substrates make this method the most reliable and most sensitive phosphodiesterase assay described to date. Because of the simplicity, specificity, and high sensitivity obtainable with these assay methods using 32-P-labeled substrates, we have also devised simple conditions for the preparation and purification of [alpha-32-P] ATP, cyclic [32-P] AMP and cyclic [32-P] GMP with specific activities in excess of 100 Ci/mmol. These high specific activity 32-Plabeled cyclic nucleotides are important for these new assay methods and are also useful to follow purification recovery of endogenous cyclic AMP and cyclic GMP from biological materials before protein binding or radioimmunological isotope displacement assays when performed in the femtomole range.
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PMID:Assay for adenylate cyclase and cyclic nucleotide phosphodiesterases and the preparation of high specific activity 32-P-labeled substrates. 16 81


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