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)

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

Adenosine triphosphatase (ATPase) activities were compared in platelets of asthmatic and nonasthmatic children. Significantly elevated Mg2+- and Ca2+-dependent ATPase activities were found in particulate and soluble fractions of platelets from nonsteroid-treated asthmatic children compared to steroid-treated asthmatic and nonasthmatic children. The most pronounced increase (greater than twofold) occurred in the Ca2+-ATPase of the soluble fraction which contains platelet contractile protein. Intact cell surface of ecto ATPase activity was not significantly increased in platelets of asthmatic children. The findings are consistent with adrenergic imbalance in asthma involving depressed adenylate cyclase activity (beta-adrenergic) and increased ATPase activity (alpha-adrenergic) and may relate to abnormal platelet aggregation patterns.
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PMID:Increased adenosine triphosphatase activity in platelets of asthmatic children. 12 27

1. Six rat liver plasma-membrane subfractions of different density and morphological, enzymic and chemical properties were prepared from homogenates by a combination of differential, rate-zonal and density-gradient centrifugation. They consisted of three vesicular 'light' subfractions of density 1.12-1.13 and three 'heavy' subfractions of density 1.16-1.18 containing membrane strips and intercellular junctions. 2. All six subfractions contained a basal adenylate cyclase activity. One of the 'light' subfractions that showed the highest glucagon-stimulated adenylate cyclase activity was identified as deriving form the blood-sinusoidal face of the hepatocyte. This subfraction, unlike the others, was contaminated by Golgi components, as indicated by its morphological properties and the presence of galactosyl- and sialyl-transferase activities. 3. All the six subfractions showed high activities of the following plasma-membrane marker enzymes: 5'-nucleotidase, alkaline phosphodiesterase (nucleotide pyrophosphatase), alkaline phosphatase, leucine naphthylamidase and Mg2+-activated adenosine triphosphatase. A 'light' subfraction that showed the highest specific activities of all the above marker enzymes, but lacked a glucagon-stimulated adenylate cyclase activity, was identified as deriving from the bile-canalicular face of the hepatocyte. 4. The 'heavy' subfractions, which showed generally the lowest activities of the above plasma-membrane enzyme markers, and were characterized by the presence of desmosomes and gap junctions, were taken to originate from the contiguous faces of the hepatocyte. 5. The protein composition of the six subfractions was generally similar, as shown by polyacrylamide-gel electrophoresis. Differences in the amounts of various protein and glycoprotein bands among the subfractions correlated with their morphology, enzymic composition and sialic acid content. 6. Hormonal and histochemical evidence supporting the identification of a bile-canalicular subfraction, a blood-sinusoidal subfraction and contiguous-face subfractions is discussed.
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PMID:Functional polarity of the rat hepatocyte surface membrane. Isolation and characterization of plasma-membrane subfractions from the blood-sinusoidal, bile-Canalicular and contiguous surfaces of the hepatocyte. 12 84

Some effects of salts on the adenylate cyclase of partially purified plasma membranes from rat liver have been studied. Under conditions where cyclic adenosine 3':5'-monophosphate formation was linear with respect to time and protein concentration, the enzyme was stimulated 3- to 6-fold by 10 mM NaF, 10- to 30-fold by 1 muM glucagon, 4- to 5-fold by 0.1 mM 5'-guanylylimidodiphosphate, and in the presence of 3 muM GTP, 2-fold by 10 mug/ml of prostaglandin E1. Various salts were found to stimulate basal activity slightly, but enhanced the response to NaF 3- to 4-fold, to glucagon 1.5- to 2-fold, to 5'-guanylylimidodiphosphate 2- to 3-fold, and to prostaglandin E1 1.5-fold. This enhancement was observed at maximally effective concentrations of each of the respective activators. Of the salts tested, NaN3 and the Na- or K-halides were most effective. Their action appeared to be due to the respective anions. Stimulation was detectable with 1.5 mM NaN3 or 3 mM NaCl and was maximal with 30 mM NaN3 or 60 mM NaCl. The stimulatory effect of NaN3 was not due to ATP-sparing, nor to an altered cyclic adenosine 3':5'-monophosphate recovery. It was independent of the chromatography and assay methods used, and was therefore not due to procedural artifact. Fluoride-stimulated cyclase activity was enhanced by salts to a greater degree than were 5'-guanylylimidodiphosphate-, glucagon-, or (prostaglandin E1 + GTP)-stimulated activities. The effects of NaN3 were not the result of significant changes in the enzyme's responses to GTP, which increased basal and glucagon-stimulated activities but inhibited F--stimulated activity. The effects of NaN3 were greater when cyclase was assayed with Mn2+ than with Mg2+. The facilitatory effect of NaN3 or NaCl on fluoride-stimulated adenylate cyclase activity was partially reversible as was the stimulatory effect of fluoride in the presence of NaN3. Enhancement of hormonal stimulation by NaN3 was also demonstrable with cardiac and adipose tissue adenylate cyclase. However, NaN3 did not stimulate detergent-dispersed adenylate cyclases from either liver plasma membranes or brain. The data suggest that stimulation of adenylate cyclase by salts may require the added presence of other stimulatory agents and an intact membrane structure.
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PMID:Liver membrane adenylate cyclase. Synergistic effects of anions on fluoride, glucagon, and guanyl nucleotide stimulation. 12 55

We studied hearts from sham-operated and uninfected catheterized rabbits as well as from rabbits at early and late stages of cardiomyopathy and failure after 3 and 6 days of infection with Streptococcus viridans. No ultrastructural abnormalities or biochemical changes in membrane and myofibrillar activities were seen in 3-day uninfected hearts. In 6-day uninfected hearts there were decreased sarcolemmal M2+ ATPase, Na+-K+ ATPase, adenylate cyclase and calcium binding, microsomal calcium binding and uptake, and myofibrillar Ca2+-stimulated ATPase as well as increased mitochondrial calcium uptake. Slight ultrastructural changes also were apparent in 6-day uninfected hearts. At both early and late stages of infective cardiomyopathy and failure there were varying degrees of depression in sarcolemmal Mg2+ ATPase, Na+-K+ ATPase, adenylate cyclase and calcium binding, microsomal calcium binding, calcium uptake and basal ATPase, and myofibrillar Ca2+-stimulated ATPase activities. However, sarcolemmal Ca2+ ATPase and myofibrillar Mg2+ ATPase activities were decreased only after 6 days of infection. Mitochondrial calcium binding and uptake were increased in early stages but decreased in late stages of disease. Furthermore in infected hearts there were defects in mitrochondrial respiration and phosphorylation. Generalized severe myocardial cell damage involving myofibrils, mitochondria, and the sarcotubular system was seen only in late stages of infection. The results demonstrate impairment of different membrane and contractile protein functions as well as ultrastructural abnormalities in bacterial cardiomyopathic hearts which were absent or of lesser magnitude in hearts with only hypertrophy. The findings reported here suggest to use that there is an association between heart failure and changes in function of cellular components during bacterial infective cardiomyopathy.
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PMID:Abnormalities in heart membranes and myofibrils during bacterial infective cardiomyopathy in the rabbit. 13 11

1. The activities of some membrane-bound enzymes such as adenylate cyclase, Na+ + K+-stimulated adenosine triphosphatase (Na+ + K+-ATPase), Ca2+-stimulated ATPase and Mg2+-stimulated ATPase were examined in heart sarcolemmal fractions from control and cardiomyopathic hamsters at different stages of heart failure. 2. The basal adenylate cyclase activity in sarcolemma from cardiomyopathic animals with early, moderate and late stages of heart failure was not different from the control values whereas the sodium fluoride- and catecholamine-stimulated adenylate cyclase activities were depressed in cardiomyopathic sarcolemma at moderate and late stages. 3. The sarcolemmal Na+ + K+-ATPase activity was decreased and the non-specific phosphatase activity was increased at early, moderate and late stages of heart failure. 4. The sarcolemmal Ca2+-ATPase activity was decreased at moderate and late stages whereas the Mg2+-ATPase activity was decreased at the late stages of heart failure only. 5. A marked decrease was found in calcium binding by heart sarcolemma from cardiomyopathic hamsters at late stages of failure. 6. These results suggest that dramatic sarcolemmal changes are associated with heart failure, and support the view that membrane abnormalities play a crucial role in the development of myocardial dysfunction, cyclase, calcium binding, heart failure, heart membranes, sarcolemmal enzymes.
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PMID:Comparison of heart sarcolemmal enzyme activities in normal and cardiomyopathic (UM-X7.1) hamsters. 13 61

A procedure for the isolation of plasma-membrane-enriched fractions from bovine 'pars intermedia' and neurohypophysis is described. Various fractions are isolated by differential centrifugation and discontinuous sucrose density gradients. The plasma-membrane-enriched fractions have a density in sucrose of 1.14 and 1.16 and the yields are 1.8 mg and 1.5 mg per gram of tissue for the pars intermedia and neural lobe, respectively. The fractions are characterized by electron microscopy and enzymatic assays. The plasma membrane fractions are mainly vesicular in nature and are free of nuclei, mitochondria, and microsomes when examined by electron microscopy. 5'-Nucleotidase (EC 3.1.3.5) and Mg2+-(Na+ + K+)-ATPase (EC 3.6.1.3) activities are concentrated in the plasma-membrane-enriched fraction. Also, adenylate cyclase (EC 4.61.1) shows a 5 to 10-fold purification in the isolated membrane fraction. NaF (10mM) gives a two to three-fold stimulation of enzymatic activity in all fractions studied The yields of adenylate cyclase, 5'-nucleotidase, and Mg2+-(Na+ +K+)-ATPase are about 6% in the membrane fraction.
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PMID:Purification of plasma membrane fractions from the bovine pars intermedia and neurohypophyseal lobe and properties of associated adenylate cyclase. 14 70

At constant 1 mM-ATP, the Mg2+-saturation curves for adenylate cyclase (EC 4.6.1.1) particulate preparations obtained from corpus striatum and cortex tissues of rat brain show that addition of 0.1 mM-noradrenaline increases the apparent Vmax. for Mg2+ by 300% in corpus striatum particles, and by 280% in cortex particles. At 10 mM-MgCl2, the addition of 0.1 mM-noradrenaline increased by 800% the adenylate cyclase activity of corpus striatum particles. At all Mg2+ concentrations, the addition of 0.3 mM-CaCl2 suppressed the noradrenaline-induced stimulation of adenylate cyclase of corpus striatum particles, and even resulted in a strong inhibition of the activating effect of Mg2+ itself on adenylate cyclase of corpus striatum particles, and even resulted in a strong inhibition of the activating effect of Mg2+ itself on adenylate cyclase activity of cortex particles. The addition of noradrenaline during a 3 h preincubation of particle preparations of brain cortex at 38 degrees C decreased by more than 4-fold the half-life of the decay of adenylate cyclase activity. The addition of MgATP protected against noradrenaline-induced inactivation.
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PMID:Effects of noradrenaline on the activation and the stability of brain adenylate cyclase. 14 58

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

The effects of sodium pentobarbital on ATPase, Ca2+ binding and adenylate cyclase activities of the rat heart sarcolemmal preparations were investigated. The Na+ - K+ ATPase activity was diminished by pentobarbital in concentrations as low as 0.3 mM. Mg2+ ATPase, Ca2+ ATPase and adenylate cyclase activities were also depressed but required 10 to 15 mM of this agent. Pentobarbital in concentrations of 10 mM, however, caused an increase in sarcolemmal Ca2+ binding. Mitochondrial and microsomal ATPase activities were decreased by 1 and 5 mM concentrations of pentobarbital respectively, while myofibrillar ATPase activity was unaltered even at a concentration of 20 mM. These data suggest that cardiodepressant effects of high doses of pentobarbital may partly be explained on the basis of its actions on heart sarcolemma.
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PMID:Effects of sodium pentobarbital on rat heart sarcolemma. 15 80


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