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)

Pancreas of the cat was fractionated into its subcellular components by centrifugation through an exponential ficoll-sucrose density gradient in a zonal rotor. This enables a preparation of four fractions enriched in plasma membranes, endoplasmic reticulum, mitochondria and zymogen granules, respectively. The first fraction, enriched by 9- to 15-fold in the plasma membrane marker enzymes, hormone-stimulated adenylate cyclase, (Na+K+)-ATPase, and 5'-nucleotidase, is contaminated by membranes derived from endoplasmic reticulum but is virtually free from mitochondrial and zymogen-granule contamination. The second fraction from the zonal gradient shows only moderate enrichment of the above marker enzymes but contains a considerable quantity of plasma membrane marker enzymes and represents mostly rough endoplasmic reticulum. The third fraction contains the bulk of mitochondria and the fourth mainly zymogen granules as assessed by electron microscopy and marker enzymes for both mitochondria and zymogen granules, namely succinic dehydrogenase, trypsin and amylase. Further purification of the plasma membrane fractions by differential and sucrose step-gradient centrifugation yields plasma membranes enriched 40-fold in basal and hormone-stimulated adenylate cyclase and (Na+K+)-ATPase.
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PMID:Studies on isolated subcellular components of cat pancreas. I. Isolation and enzymatic characterization. 14 36

Changes in activities of plasma membrane enzymes during liver regeneration may be related to the maintenance of hepatic function or to the regulation of cell proliferation. Plasma membranes were isolated from rat livers at various times after partial hepatectomy, and the specific activities of alkaline phosphatase, (Na+ + K+)-ATPase, leucine aminopeptidase, 5'-nucleotidase, and adenylate cyclase (basal and with glucagon or epinephrine) were measured. Alkaline phosphatase and (Na+ + K+)-ATPase activity increased 3.6-fold and 2-fold respectively, during the first 48 h after partial hepatectomy. The time of onset and duration of change suggest that these increases in activity are involved in the maintenance of bile secretion. Decreases in leucine aminopeptidase activity at 48--108 h and in 5'-nucleotidase activity at 12--24 h were observed, which may be involved in the restoration of protein and accumulation of RNA. The basal activity of adenylate cyclase increased after partial hepatectomy. The response of adenylate cyclase to epinephrine showed a transitory increase between 36 and 108 h after surgery, while the response to glucagon was decreased by approximately 50% at all time points through 324 h after surgery. These changes in the hormone responsiveness of adenylate cyclase are similar to those previously observed in fetal and preneoplastic liver.
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PMID:Changes in plasma membrane enzyme activities during liver regeneration in the rat. 14 24

The electrophysiologic properties and the negative inotropic effect of verapamil are most likely due to the inhibition of calcium movement across the sarcolemmal membrane. A possible biochemical basis for this inhibition of calcium movement was studied in a membrane fraction rich in (Na+ + K+)-ATPase (EC 3.6.1.3) and adenylate cyclase (EC 4.6.1.1) activity and which demonstrated Ca2+-ATPase (EC 3.6.1.3) activity. Since each of these enzymes has the potential for influencing transsarcolemmal calcium movements, the effect of verapamil on their activities was studied in this membrane fraction isolated from rat and guinea pig hearts. Ca2+-ATPase activity in the rat was 37.7 mumol Pi/mg per hour compared with 13.8 +/- 2.9 in the guinea pig (p less than 0.01). Corresponding values for (Na+ + k+)-atpase activites were 7.9 +/- 0.9 mumol Pi/mg per hour versus 10.2 +/- 1.4. Adenylate cyclase activity in the rat was 240 +/- 8 pmol/mg per minute compared with 299 +/- 27. It was found that verapamil in concentrations of 0.01-100 mg/litre (2.1 X 10(-8) to 2.1 X 10(-4) M) had no effect on the activity of the above enzymes in either species and it was concluded that a biochemical basis for the effect of verapamil on calcium flux has yet to be defined.
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PMID:Effects of verapamil on (Na+ + K+)-ATPase, Ca2+-ATPase, and adenylate cyclase activity in a membrane fraction from rat and guinea pig ventricular muscle. 14 48

Liposomes prepared with cholesterol and dipalmitoyl phosphatidylcholine were incubated with a clone of normal rat kidney fibroblast of cells in culture. The cells took up [14C]cholesterol in proportion to the concentration of liposomes in the incubation medium, and the uptake increased with time over the four hours of study. Two cell membrane enzymes, adenylate cyclase and (Na+ + K+)-ATPase, exhibited decreased activity after treatment with cholesterol-containing liposomes. The decrease in adenylate cyclase activity was directly proportional to the uptake of [14C]cholesterol. When a variety of subclones of NRK 5W were examined some were found to respond to cholesterol treatment and some did not. These data are consistent with the view that membrane cholesterol content plays a role in controlling the activity of some plasma membrane enzymes.
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PMID:Effect of liposomes containing cholesterol on adenylate cyclase activity of cultured mammalian fibroblasts. 14 76

Red blood cell plasma membranes contain a number of enzymes: ATPases, anion transport protein, glyceraldehyde 3-phosphate dehydrogenase, protein kinases, adenylate cyclase, acetylcholinesterase. Most of them are tightly bound to the membrane and are present in small amounts. As a result, structural characterization of erythrocyte membrane enzymes has not yet been successful. Functional studies have, however, yielded a great deal of information. ATPases allow active transport of cations (calcium, sodium, potassium). Anion transport protein controls movements of chloride and phosphate ions, and of glucose and water. Among glycolytic enzymes: glyceraldehyde 3-phosphate dehydrogenase is partially bound to the membrane. Protein kinases catalyze the phosphorylation of several membrane proteins, one of which (spectrin) is involved in red blood cell mechanical properties. The physiological role of adenylate cyclase is unknown. Acetylcholinesterase is an ectoenzyme. Calcium-dependent ATPase, adenylate cyclase and phosphorylation of erythrocyte membrane proteins have been found abnormal in various conditions: hereditary spherocytosis, sickle-cell anemia, progressive muscular dystrophies, all of these disorders being associated with a decreased deformability of the erythrocyte.
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PMID:The enzymes of the red blood cell plasma membrane. 14 25

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

The regulation of adrenergic receptors in rat heart was measured in rats made hyperthyroid by injection with thyroxine and made hypothyroid by addition of propylthiouracil to the drinking water. Hyperthyroid rats display cardiac hypertrophy and a decrease in epididymal fat pad weight. The maximal beta-receptor level of ventricular membranes, as determined by (-)-[3H]dihydroalprenolol binding, was increased 60% by thyroxine treatment and decreased about 30% by propylthiouracil treatment. The affinity of the beta receptor was unchanged after thyroxine or propylthiouracil treatment. The maximal activity of the isoproterenol-stimulated adenylate cyclase (EC 4.6.1.1) varied with thyroid state in a manner parallel to the increase in beta-adrenergic binding sites. Thyroxine treatment also increases by 2-fold the beta receptors in isolated rat fat cells. Propylthiouracil treatment lowered the level of alpha receptors in heart by 30% as measured by [3H]dihydroergocryptine binding, but increased the affinity about 2.5-fold. The highest level of alpha receptors was seen in control hearts. These studies indicate that thyroxine may control the turnover of beta-adrenergic receptors in heart and fat cells and regulate physiological responses in these tissues via a hormone-hormone interplay system. Thyroxine treatment reduced the activity of the membrane-bound Mg2+-ATPase (EC 3.6.1.3) and 5'-mononucleotidase (EC 3.1.3.5) but appears to increase the activity of the (Na+ + K+)ATPase (EC 3.6.1.4).
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PMID:Hormone action at the membrane level. VIII. Adrenergic receptors in rat heart and adipocytes and their modulation by thyroxine. 14 63

Cytochemical techniques have been employed to study the localization of adenylate cyclase and (Ca2+ + Mg2+)-stimulated ATPase activities in platelets after fixation. Biochemical analysis of adenylate cyclase demonstrated a 70% reduction in activity in homogenates from fixed cells, but the residual activity could be stimulated 10--20 times by prostaglandin E1 (1 micrometer) under the same incubation conditions as employed in the cytochemical studies (e.g. media containing 2 mM lead nitrate and 10 mM NaF). Adenylate cyclase activity employing 5'-adenylyl-imiodiphosphate (AMP-P(NH)P) as substrate was found to be associated with the dense tubular system (smooth endoplasmic reticulum) in intact fixed platelets, and was apparent only when the cells were incubated with prostaglandin E1. Less activity was found along the membranes of the surface connected open canalicular system and occasionally at the outer cell surface. Enzymatic activity was blocked by the adenylate cyclase inhibitor 9-(tetrahydro-2-furyl) adenine and was not due to AMP-P(NH)P phosphohydrolase activity. The low adenylate cyclase activity in the surface membranes may be due to enzyme inactivation as a result of fixation, since a surface membrane fraction obtained by the glycerol lysis technique from unfixed cells had an adenylate cyclase specific activity equivalent to that in the microsomal membrane fraction. (Ca2+ + Mg2+)-stimulated ATPase activity was found associated with the membranes of the surface connected open canalicular system in unfixed cells. After brief fixation (5--15 min) with glutaradehyde, strong (Ca2+ + Mg2+)ATPase activity became apparent in the dense tubular system. Longer periods of fixation inactivated enzymatic activity. Addition of Ca2+ (1.0 mM) to incubation medium with low Mg2+ (0.2 mM), or increasing Mg2+ to 4.0 mM, in both cases strongly stimulated enzyme activity. The ATPase activity in the platelet membranes was not inhibited by ouabain. It is suggested that the Ca2+-stimulated ATPase and adenylate cyclase activities in the dense tubules may possibly be involved in regulation of intracellular Ca2+ transport.
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PMID:Cytochemical localization of adenylate cyclase and of calcium ion, magnesium ion-activated ATPases in the dense tubular system of human blood platelets. 15 Aug 66

1. Pancreatic plasma membranes containing a high adenylate cyclase activity and a low contamination by cytochrome c oxidase were isolated from the rat by sucrose density centrifugation. The preparation contained an (Mg,Ca)-ATPase of high activity with the following characteristics. 2. The ATPase activity was shown to have two apparent Km values for Mg-ATP (0.24 +/- 0.09 mM and 1.15 +/- 0.21 mM) and two apparent Km values for Ca-ATP (0.14 +/- 0.09 mM and 0.68 +/- 0.10 mM). Mg-GTP and Ca-GTP were also hydrolysed by the preparation. The phase transition temperature was 19.3 +/- 1.0 degrees C for the Mg-ATPase and 22.6 +/- 1.1 degrees C for the Ca-ATPase activities. 3. Three lines of evidence suggest that Mg-ATP and Ca-ATP were substrates for the same enzyme: Mg-dependent and Ca-dependent activities were not additive; the two activities showed the same pH optimum at 8.0; and the nonionic detergents Triton X-100, Triton X-305, Triton N-101, Lubrol P 12 A, and digitonin, produced a parallel solubilization of the two activities. 4. Enzyme activities were insensitive to potassium, sodium, ouabain, pancreozymin, carbamoyl-choline, secretin, concanavalin A, wheat germ agglutinin, and soybean lectin.
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PMID:Characterization of (Mg,Ca)-ATPase activity in rat pancreatic plasma membranes. 15 27

Platelets were examined to enable a simultaneous investigation to be made of indolylamine and electrolyte metabolism in affective disorder. No significant differences were detected in either platelet membrane ATPase or adenyl cyclase specific activity in any of the groups of patients studied, when compared with appropriate controls. A reduced Vmax and y for the 5-hydroxy-tryptamine uptake process into platelets was observed in both unipolar and bipolar depressed groups. The Km for this process was not significantly different in any of the patients from that found in control subjects. Lithium therapy was shown not to influence significantly any of the platelet parameters examined. It is suggested that membrane enzyme changes found in some peripheral cells in patients suffering from affective disorder, i.e. reduced Na+ + K+ - ATPase activity in erythrocytes in depression, is not common to all peripheral cells and may or may not reflect central nervous system changes.
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PMID:Studies on human blood platelets in affective disorder. 15 82


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