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)

Specific cell surface membrane receptors, labeled by forming a complex with low concentrations (about 10--9 M to 10--10 M) of a highly radioactive (125-I, carrier-free) ligand, can serve as simple, reliable, sensitive, and quantitative markers for plasma membranes in fractionation procedures. 125-I-Labeled insulin, cholera toxin and the plant lictins, wheat germ agglutinin (WGA), and concanavalin A are the receptor ligands used for labeling plasma membranes. Plasma membranes are labeled before homogenization by incubating intact cells briefly at 24 degrees or 4 degrees, or by very brief in situ perfusion of the organ, with the 125-I-Labeled marker. After removing the free 125-I-labeled ligand from the medium by washing (at 4 degrees), the membrane-marker complex remains intact over prolonged (days) periods of time at 4 degrees. Labeling occurs nearly exclusively on the cell surface, the specificity of this plasma membrane reaction is maintained through homogenization and fractionation, and little dissociation of the complex, detectable exchange of label, or aggregation occur even upon prolonged incubation of the homogenates. When desired, the complex can be dissociated deliberately by manipulating experimental conditions such as temperature or by adding specific simple sugars. The most generally suitable marker appears to be WGA. At least in certain tissues (e. g. fat cells) labeling of the plasma membrane with 125-I-WGA and 125-I-isnulin can be performed equally well and selectively in homogenates as in the intact cell. 125-I-Cholera toxin cannot be used in homogenates because of significant binding to nuclei. The use of 125-I-labeled WGA as a specific plasma membrane marker is illustrated in following the course of fractionations, and in quantitating the yield and purity, of plasma membranes from fat cells, lymphocytes, and liver. The results are compared with simultaneous measurements of the plasma membrane enzyme "markers," ATPase, 5-nucleotidase, and basal as well as hormone-stimulated adenylate cyclase activities. The fractionation of liver plasma membranes by aqueous dextran-polyethylene glycol two-phase polymer systems and by conventional differential centrifugation procedures arealso quantitated with the marker, 125I-WGA. Substantial quantities of plasma membrane material are no recovered in the interphase of the two-phase polymer system. Conventional liver fractionation procedures which retain, for further purification, only the readily sedimented pellet (2000 times g, 15 min) discard a very large (at least 70%) questenal hy
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PMID:Membrane receptors as general markers for plasma membrane isolation procedures. The use of 125-I-labeled wheat germ agglutinin, insulin, and cholera toxin. 16 29

A method is described for the isolation of secondary lysosomes from homogenates of rabbit liver; The uptake of Triton WR-1339 by rabbit-liver lysosomes when administered by intraperitoneal injection was used to decrease the density of secondary lysosomes. Lysosomal fractions prepared by this method contain an NAD nucleosidase (NAD glycohydrolase, EC 3;2.25), an enzyme which has previously been considered to be associated with other subcellular fractions. The enzyme has maximum activity at pH 6 and cleaves both NAD and NADP. It is inhibited by nicotinamide (Ki equals 4.5 mM) and by HgCl2. Both nucleosidase and 2'-nucleotidase show in-vitro latency typical of lysosomal acid hydrolases. Rabbit-liver plasma-membrane fractions were isolated which contained most 5'-nucleotidase but relatively little nucleosidase, whereas rabbit liver lysosomes contain both 5'-nucleotidase and nucleosidase enzymes but little adenyl cyclase.
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PMID:Evidence for NAD nucleosidase in rabbit-liver lysosomes. 23 77

Previous studies have indicated that rat luteal cells at certain stages of development can be fractionated so as to obtain two plasma membrane fractions with different densities and different profiles of marker enzymes. The light membrane fractions (density 1.13) contain the majority of hCG-binding sites and little or no cyclase enzyme, while the heavy membranes (density 1.17) contain the majority of cyclase enzyme and lesser quantities of hormone-binding sites. These membrane fractions were further compared with respect to their susceptibility to perturbation by digitonin. The buoyant density of luteal cell light membrane fractions, as marked by [125I]iodo-hCG binding, Mg2+-dependent ATPase, and 5'-nucleotidase, were highly perturbable by digotonin (delta density, greater than 0.05), while adenylate cyclase activity and phosphodiesterase activity associated with this fraction were only slightly perturbed (delta density, less than 0.02). The buoyant density of luteal cell heavy membrane fractions, as marked by adenylate cyclase, ATPase, and nucleotidase, was not significantly perturbed by digotonin. The hCG binding associated with the heavy membrane fraction was not perturbed by digitonin. From these studies, we conclude that the adenylate cyclase activity associated with light membrane fractions is due to contamination by heavy membranes, while the hCG-binding activity in heavy membrane fractions is intrinsic to that membrane. Except for the lysosomal marker (glucuronidase), which was solubilized by digitonin, the detergent had no significant effect on the density of mitochondrial, Golgi, GERL (Golgi, endoplasmic reticulum, and lysomal), or endoplasmic reticulum membranes. Plasma membranes from isolated granulosa cells and ovaries obtained 24 h after priming with PMS gonadotropin-hCG behaved as heavy membranes (density, 1.17) which contained hCG-binding sites, adenylate cyclase, nucleotidase, and Mg2+-dependent ATPase. These were not significantly perturbed by digitonin. The appearance of light membranes and the segregation of adenylate cyclase from the majority of hCG-binding sites is a development feature of the luteal cell.
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PMID:Interactions of gonadotropins with corpus luteum surface membranes. V. Differential effects of digitonin on the buoyant densities of light and heavy rat ovarian membrane fractions. 43 71

The amphiphilic cationic cardioactive drugs (pindolol, propranolol and amiodarone) were tested for their effects on lipid dynamics (measured by fluorescence depolarization) and on enzymatic activities up to 1 mM in purified cardiac sarcolemmal vesicles from adult rat. The vesicles were enriched 12- to 37-fold (with respect to tissue homogenate) in Na+/K+ ATPase, K+-stimulated p-nitrophenylphosphatase, 5'nucleotidase and adenylate cyclase, all of which are believed to be components of sarcolemma. Phospholipids and cholesterol content were enriched 5- and 13-fold respectively. There was very little contamination of the sarcolemmal vesicles by sarcoplasmic reticulum (as judged by Ca2+ ATPase and glucose-6-phosphatase activities) or mitochondria (as judged by cytochrome-c-oxidase activity). Pindolol had no effect on lipid dynamics and enzyme activities except for the isoproterenol-stimulated adenylate cyclase. The latter was also totally inhibited at 1 microM by propranolol which inhibited Mg2+ ATPase and increased fluidity above 20 microM. Amiodarone affected all the enzyme activities (except Na+/K+ ATPase): isoproterenol-stimulated adenylate (IC50 = 30 microM), Mg2+ ATPase (IC50 = 20 microM) and K+-stimulated-p-nitrophenylphosphatase were inhibited; 5'nucleotidase was activated above 2 microM. By contrast with propranolol, amiodarone decreased lipid mobility. The effect was linear with the concentration of the drug above 1 microM.
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PMID:Differential effects of amiodarone and propranolol on lipid dynamics and enzymatic activities in cardiac sarcolemmal membranes. 253 21

The activity of sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase) is considerably higher in homogenates of outer medulla than in the cortex or papilla of the kidney. The enzyme has similar kinetic characteristics in both cortex and medulla, and binds ouabain in the same proportion. The discrepancy in enzymatic activity is not paralleled by similar change in the activity of adenyl cyclase, 5'nucleotidase, glucose-6-phosphatase, or succinic dehydrogenase. Na-K-ATPase is also higher in distal convoluted tubules (ventral slices) than in the proximal tubules (dorsal slices) of the kidney of Amphiuma. The high concentration of Na-K-ATPase in the red medulla of the kidney is probably related to the presence here of the thick ascending limb of the loop of Henle, and this has important implications with regard to the mechanism of sodium reabsorption by different portions of the nephron.
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PMID:The distribution of sodium-potassium--activated adenosine triphosphatase in medulla and cortex of the kidney. 432 13

Differences in the pattern of the development of three enzymes of the plasma membrane have been established. The activity of Na, K-ATPase progressively increases, that of adenylate cyclase decreases, whereas the activity of 5-nucleotidase undergoes only slight changes during embryogenesis. Differences between these enzymes were also found with respect to the development of their sensitivity to the regulatory effects of catecholamines. Adrenaline reactivity of adenylate cyclase may be detected already in embryogenesis; it is lower than that in definite muscle tissue increasing during further ontogenesis. Catecholamine reactivity was not found in Na, K-ATPase and 5-nucleotidase up to the 17th day of incubation of chick embryos. The effect of adrenalin was observed at later stages of ontogenesis, it may be initiated by exogeneous cAMP and protein kinase. At postembryonic stages, similarity in the behavior of these enzymes was found with respect to the presence and pattern of their reaction to adrenalin (stimulation), as well as with respect to temporal dynamics of the effect. The data obtained indicate the existence of close connections between these enzymes, which are realized in the sequence adrenoreceptor-adenylate cyclase-cAMP-protein kinase-effector proteins.
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PMID:[Role of the hypothalamus and pituitary gland in the development of pancreatic islet sensitivity to glucose in fetal rats]. 626 78

Pressure overload left ventricular (LV) hypertrophy was produced by banding the ascending aorta of puppies and allowing them to grow to adulthood. LV free wall weight per body weight increased by 87% from a normal value of 3.23 +/- 0.19 g/kg. Hemodynamic studies of conscious dogs with LV hypertrophy and of normal, conscious dogs without LV hypertrophy showed similar base-line values for mean arterial pressure, heart rate, and LV end-diastolic pressure and diameter. LV systolic pressure was significantly greater, P less than 0.01, and LV stroke shortening was significantly lss, P less than 0.01, in the LV hypertrophy group. In both normal and LV hypertrophy groups, increasing bolus doses of norepinephrine or isoproterenol produced equivalent changes in LV dP/dt. beta-adrenergic receptor binding studies with [3H]-dihydroalprenolol ( [3H]DHA) indicated that the density of binding sites was significantly elevated, P less than 0.01, in the hypertrophied LV plasma membranes (111 +/- 8.8, n = 8), as compared with normal LV (61 +/- 5.6 fmol/mg protein, n = 11). The receptor affinity decreased, i.e., disassociation constant (KD) increased, selectively in the LV of the hypertrophy group; the KD in the normal LV was 6.8 +/- 0.7 nM compared with 10.7 +/- 1.8 nM in the hypertrophied LV. These effects were observed only in the LV of the LV hypertrophy group and not in the right ventricles from the same dogs. The plasma membrane marker, 5' -nucleotidase activity, was slightly lower per milligram protein in the LV hypertrophy group, indicating that the differences in beta-adrenergic receptor binding and affinity were not due to an increase in plasma membrane protein in the LV hypertrophy group. The EC50 for isoproterenol-stimulated adenylate cyclase activity was similar in both the right and left ventricles and in the two groups. However, maximal-stimulated adenylate cyclase was lower in the hypertrophied left ventricle. Plasma catecholamines were similar in the normal and hypertrophied groups, but myocardial norepinephrine was depressed in the dogs with LV hypertrophy (163 +/- 48 pg/mg) compared with normal dogs (835 +/- 166 pg/mg). Thus, severe, but compensated LV hypertrophy, induced by aortic banding in puppies, is characterized by essentially normal hemodynamics in adult dogs studied at rest and in response to catecholamines in the conscious state. At the cellular level, reduced affinity and increased beta-adrenergic receptor number characterized the LV hypertrophy group, while the EC50 for isoproterenol-stimulated adenylate cyclase activity was normal. By these mechanisms, adequate responsiveness to catecholamines is retained in conscious dogs with severe LV hypertrophy.
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PMID:Effects of pressure overload, left ventricular hypertrophy on beta-adrenergic receptors, and responsiveness to catecholamines. 632 5

Guanyl-5'-yl imidodiphosphate (Gpp(NH)p), a nucleotide phosphohydrolase-resistant analog of GTP, caused inhibitory and stimulatory effects on the basal adenylate cyclase activity of rat synaptosomal fractions when manganese was present in the assay mixture, whereas the nucleotide caused only a stimulatory effect when magnesium was employed. In the presence of manganese, the inhibitory and stimulatory effects of Gpp(NH)p could be seen at around concentrations of 10(-7) M and 10(-4) M Gpp(NH)p, respectively. The inhibitory and stimulatory effects of Gpp(NH)p were both antagonized competitively by GTP; these effects of the analog were the opposite of those observed with GTP, which was stimulatory and inhibitory for fat call adenylate cyclase at 10(-7) M and 10(-4) M, respectively (Yamamura, H., Lad, P.M., and Rodbell, M. (1977) J. Biol. Chem. 252, 7964--7966). The degree of inhibition by Gpp(NH)p did not depend on the concentration of manganese nor on the addition of ethylene glycol bis(beta-aminoethyl ether)-N, N, N', N'-tetraacetic acid.
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PMID:Inhibitory and stimulatory effects of guanyl-5'-yl imidodiphosphate on the adenylate cyclase activity of rat synaptosomal fractions. 735 34

Research on dietary polyunsaturated fatty acids (PUFA), on the activity of 5'nucleotidase and adenylate cyclase are largely contradictory due, mostly, to the absence of adequate control group. In this study; four different diets have been evaluated on the 5'nucleotidase and adenylate cyclase activities in rat liver plasma membranes. Wistar rats were given a semisynthetic diet in which lipids were supplied by 5% of either peanut oil (n-3 PUFA deficient diet), cod liver oil (n-6 PUFA deficient diet) partially hydrogenated palm oil (total PUFA deficient diet) and a mixture of peanut and rapeseed oil (control group). Liver plasma membranes were separated by using a Percoll gradient in a Beckman JA 20 centrifuge. 5'nucleotidase and adenylate cyclase activities were measured in a liquid scintilation detector by following the degradation of 3HAMP (adenosine monophosphate) and production of 3HcAMP (cyclic adenosine monophosphate) respectively. Animals fed the total PUFA deficient diet exhibited significant lower body weight and lower liver weight than did the control group. Low cholesterol concentrations were observed in animals deficient either in n-3 or total PUFA in relation to the control group. All dietary deficiencies studies provoked reduced phospholipid levels. Phosphatidylcholine and phosphatidylethanolamine were not modified whatever the deficiency studied. Phospholipids fatty acid composition was significantly modified by the diets studied. The specific activity of 5'nucleotidase in hepatic plasma membrane was independent of dietary PUFA. The catalytic unit of adenylate cyclase complex in totally deficient animals was augmented. The unit of the enzyme stimulated by the guanydyl imidodiphosphate (GppNHp) in n-3 PUFA deficient animals was augmented and reduced in animals receiving the n-6 PUFA deficient diet. In conclusion, our results show that each dietary PUFA deficiency modifies differently the proportions of phospholipid classes and their fatty acid composition. The mechanisms responsible for these modification remain to be elucidated. However, the phospholipid fatty acid changes did not influence the 5'nucleotidase activity except in the case of extreme excess which concerns more toxicology than nutritional modifications. Finally, the catalytic unit (Forskoline + GDP beta s) of adenylate cyclase complex and the regulatory unit (GppNHp) may be sensitive to alterations in PUFA composition.
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PMID:Polyunsaturated fatty acid deficiencies: effects on hepatic plasma membrane fatty acid composition and enzyme activity. 916 45

The incidence of polyunsaturated fatty acids (PUFA) in human nutrition is now generally accepted. As essential membrane components, PUFA may act as enzyme activity modulators. In this study, four different diets, in which PUFA type was the only modifying factor, were evaluated on 5'nucleotidase, adenylate cyclase and Na+/K+ATPase activities in rat brain plasma membranes. Animals fed the total PUFA deficient diet exhibited significant lower body weight and lower brain weight than did the control group. The specific activities of 5'nucleotidase and Na+/K+ATPase in brain plasma membrane were slightly modified by dietary PUFA. The catalytic unit of adenylate cyclase in total PUFA deficient animals presented augmented enzyme activity and animals receiving diets deficient in n-6 PUFA showed reduced activity in relation to the control animals. Our results showed that the epinephrine receptors, in the case of adenylate cyclase are not modified by dietary PUFA, but rather the catalytic unit seems to be altered by dietary PUFA. These results can be partially explained by the fluidity that PUFA confers to membranes facilitating the proximity of enzyme-substrate. The physiological consequences of dietary PUFA incidence on enzyme activity needs further study.
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PMID:Effects of dietary polyunsaturated fatty acids on adenylate cyclase, 5'nucleotidase and Na+K(+)-ATPase activities in rat brain-plasma membrane. 1034 92


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