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)

Colchicine effect has been tested on rat liver plasma membrane-bound enzymes after in vitro or in vivo treatment. It appears that the in vitro treatment does not affect 5'-nucleotidase, Mg2+-ATPase and (Na+ + K+)-ATPase, whereas adenylate cyclase is sensitive to both in vitro and in vivo treatment, the latter condition being also effective for 5'-nucleotidase.
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PMID:Effect of colchicine on rat liver plasma membrane. 610 80

Purified virions of HVJ (Sendai virus) were found to contain a guanylate cyclase activity that converts GTP to cyclic GMP. Activities of adenylate cyclase and 5'-nucleotidase which are frequently used as marker enzymes of cell membranes were not detected in the virus. Guanylate cyclase and virion-associated activities, neuraminidase and hemagglutinin, were co-purified during a purification of virions. Guanylate cyclase activity was not detected without disruption of the virions with a detergent, Triton X-100 or Nonident P-40. Treatment of intact HVJ with a proteolytic enzyme, trypsin or chymotrypsin, destroyed both neuraminidase and hemagglutinin; however, most of the guanylate cyclase ws retained. Guanylate cyclase activity was found in fractions containing nucleocapsids after sucrose density gradient centrifugation of disrupted virions. These results indicated that the enzyme was tightly bound to cores of HVJ and, therefore, its presence could not be explained by binding of host cell enzyme to the surface of virions. Properties of the virus-derived enzyme and particulate fractions of host cell homogenates were similar. Antiserum against nucleocapsids of HVJ inhibited guanylate cyclase activity of HVJ and particulate fractions of cells such as chorioallantoic membrane and rat liver, while soluble guanylate cyclase was not inhibited by antiserum. The biological significance and origin of guanylate cyclase found in HVJ are obscure and await further study.
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PMID:Evidence for guanylate cyclase activity associated with hemagglutinating virus of Japan (Sendai virus). 610 29

The fetal sheep heart responds to beta-adrenergic stimuli; however, in vivo studies show the response of the fetal heart is less than that of the adult heart. We used [3H]dihydroalprenolol (DHA) to study directly beta-adrenergic receptors in heart particulates of fetal sheep at term and adult sheep. [3H]DHA binding to fetal heart particulates was rapid, reversible (t 1/2 = 2.9 +/- 0.3 min), stereoselective, saturable (101.2 +/- 7.4 fmoles/mg protein), and of high affinity (4.8 +/- 0.4 nM). The rank order of agonists competing for [3H]DHA binding was isoproterenol (0.32 +/- 0.10 microM) greater than epinephrine (1.19 +/- 0.23 muM) approximately equal to norepinephrine (2.67 +/- 0.69 muM), which is compatible with beta 1-adrenergic potencies. [3H]DHA also bound to the adult sheep heart in a manner expected for beta 1-receptors. No difference in the binding affinity of [3H]DHA or agonists' competition was demonstrated between the fetal and adult sheep heart. Comparison of the concentration of beta-adrenergic receptors in fetal and adult hearts was confounded by the choice of the denominator for unit expression. The concentration was higher in the adult when expressed as a function of protein content or 5'-nucleotidase activity (0.52 +/- 0.07 versus 1.12 +/- 0.06). However, there was no difference when tissue weight, Na+ - K+-ATPase, or NaF-stimulated adenylate cyclase was used. Furthermore, isoproterenol-stimulated adenylate cyclase and cardiac contractile response to a threshold dose of isoproterenol were identical in the fetal and adult sheep heart. We conclude that beta-receptors can be studied with [3H]DHA in the fetal sheep heart, this receptor is qualitatively similar to the beta-receptor in the adult sheep heart, and it is unlikely that there is a difference in the concentration of beta-adrenergic receptors in fetal and adult sheep heart.
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PMID:Identification of beta-adrenergic receptors using [3H]dihydroalprenolol in fetal sheep heart: direct evidence of qualitative similarity to the receptors in adult sheep heart. 611 56

The effect of cholesterol and fatty acid treatment in vitro was tested on rat liver plasma membrane-bound enzymes and lipid fluidity. The observed alterations of membrane fluidity affect both (Na+-K+)-ATPase and Mg2+-ATPase activities but not 5'-nucleotidase; basal adenylate cyclase as well as its hormonal sensitivity were differentially affected by changes of membrane microenvironment.
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PMID:Effect of free fatty acids and cholesterol in vitro on liver plasma membrane-bound enzymes. 612 91

1. Isolated rat heart sarcolemma was treated with different concentrations of an ionic detergent, deoxycholate (DOC) and ATP hydrolysis in the presence of Ca2+ or Mg2+ was determined. 2. Both Ca2+-dependent ATPase and Mg2+-dependent ATPase activities were decreased in the DOC-treated membranes; however, the depression of Mg2+-dependent ATPase activity was greater than that of Ca2+-dependent ATPase. 3. The differential changes in Ca2+-dependent ATPase and Mg2+-dependent ATPase activities were apparent when incubations with DOC were carried out for different time intervals and at different temperatures. 4. In DOC-treated preparations, the Km value for Ca2+-dependent ATPase was decreased whereas that for Mg2+-dependent ATPase was increased. The half maximal velocities of the Ca2+-dependent ATPase and Mg2+-dependent ATPase enzyme reactions in the treated preparations were obtained at a DOC: membrane protein ratio of 3.0 and 0.6, respectively. 5. In the DOC-treated membranes exhibiting the half maximal velocities of enzyme reactions, the Ka value for Ca2+-dependent ATPase was drastically reduced but remained unchanged for Mg2+-dependent ATPase. 6. The DOC treatment was associated with a loss of protein as well phospholipids and resulted in changes in the ultrastructural integrity of the membrane. 7. Varying degrees of decreases in the activities of sarcolemmal adenylate cyclase. (Na+-K+)-ATPase, 5'-nucleotidase and calcium binding were seen upon DOC treatment. 8. The extent of reduction in Ca2+-dependent ATPase and Mg2+-dependent ATPase activities were also different when the membrane was treated with a non-ionic detergent, Lubrol PX. 9. These data suggest that Ca2+-dependent ATPase in heart sarcolemma is more resistant than Mg2+-dependent ATPase to detergent treatments and further indicate some differences in the properties of these enzymes.
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PMID:Ca2+- and Mg2+-dependent ATPase activities in the deoxycholate-treated rat heart sarcolemma. 612 55

The intracellular localization of adenylate cyclase and 3',5'-cyclic nucleotide phosphodiesterase in buffalo sperm was examined. Adenylate cyclase activity is distributed in heads (8.4%), midpieces (16.6%), tails (49.5%) and 5.7% in the soluble supernatant; the total recovery being 81%. A 4-fold increase in specific activity was observed in the tail fraction relative to sonicated suspension. Further fractionation of the tail fraction into plasma membrane and microtubules by dialysis against low ionic strength buffer was followed by marker enzymes (Mg2+ -ATPase, 5'-nucleotidase and alkaline phosphatase) as well as by examination of fractions under electron microscope. The recovered adenylate cyclase (79%) was found in microtubules (45%) and plasma membrane (34%). Cyclic nucleotide phosphodiesterase in tails was distributed in tail plasma membrane (13.7%), microtubules (31.5%) and cytosol (34%) with a total recovery of 80%. Similar results were obtained when the distribution of adenylate cyclase and cyclic nucleotide phosphodiesterase was studied by treatment with Triton X-100; 40% activity of adenylate cyclase present in tails (about 20% relative to sperm sonicate) appeared in the soluble form by this method. The results are discussed in relation to control of cyclic AMP levels in buffalo sperm by adenylate cyclase and cyclic nucleotide phosphodiesterase.
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PMID:Subcellular localization of adenylate cyclase of buffalo spermatozoa. 612 19

Although acute alterations in Ca2+ fluxes may mediate the skeletal responses to certain humoral agents, the processes subserving those fluxes are not well understood. We have sought evidence for Ca2+-dependent ATPase activity in isolated osteoblast-like cells maintained in primary culture. Two Ca2+-dependent ATPase components were found in a plasma membrane fraction: a high affinity component (half-saturation constant for Ca2+ of 280 nM, Vmax of 13.5 nmol/mg per min) and a low affinity component, which was in reality a divalent cation ATPase, since Mg2+ could replace Ca2+ without loss of activity. The high affinity component exhibited a pH optimum of 7.2 and required Mg2+ for full activity. It was unaffected by potassium or sodium chloride, ouabain or sodium azide, but was inhibited by lanthanum and by the calmodulin antagonist trifluoperazine. This component was prevalent in a subcellular fraction which was also enriched in 5'-nucleotidase and adenylate cyclase activities, suggesting the plasma membrane as its principal location. Osteosarcoma cells, known to resemble osteoblasts in their biological characteristics and responses to bone-seeking hormones, contained similar ATPase activities. Inclusion of purified calmodulin in the assay system caused small non-reproducible increases in the Ca2+-dependent ATPase activity of EGTA-washed membranes. Marked, consistent calmodulin stimulation was demonstrated in membranes exposed previously to trifluoperazine and then washed in trifluoperazine-free buffer. These results indicate the presence of a high affinity, calmodulin-sensitive Ca2+-dependent ATPase in osteoblast-like bone cells. As one determinant of Ca2+ fluxes in bone cells, this enzyme may participate in the hormonal regulation of bone cell function.
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PMID:A high affinity, calmodulin-responsive (Ca2+ + Mg2+)-ATPase in isolated bone cells. 613 20

Effects of adriamycin on rat heart sarcolemma were investigated by determining several membrane enzyme activities in the absence or presence of different concentrations of the drug. The adenylate cyclase activity was found to be stimulated by 0.001 and 0.01 microM of adriamycin whereas this enzyme activity was inhibited at 100 and 1000 microM concentrations of the drug. Magnesium dependent Na+, K+ ATPase was not effected by adriamycin, however, in presence of 2 mM ouabain, adriamycin (100 microM) had a depressant effect on the Na+, K+ ATPase activity. Ca2+ ATPase activity was found to be stimulated by adriamycin. The drug had no effect on the Mg2+ ATPase and 5'-nucleotidase activities. These data suggest direct as well as specific effects of adriamycin which may be important in drug-induced cardiotoxicity.
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PMID:Direct effects of adriamycin on the rat heart sarcolemma. 614 11

The subcellular localization, kinetics of activation, and substrate specificity of the guinea pig granulocyte superoxide (O2-) generating system was investigated. Membrane-enriched particles (podosomes) were made from granulocytes by mild sonication and differential centrifugation. These podosomes are enriched threefold for known plasma membrane markers, 5'-nucleotidase, and adenylate cyclase. Podosomes made from resting granulocytes have very little NAD(P)H-dependent O2- production. Podosomes made from cells stimulated with digitonin are equally enriched for membrane markers but have a 15- to 20-fold increase in NAD(P)H-dependent O2- production. The KmAPP for NADPH is one-tenth that for NADH, but the Vmax is the same. The kinetics of digitonin-stimulated whole-cell O2- production parallel the changes in enzyme activity in these podosomes. Temperature affects both the rate and extent of activation of this enzyme. The pH optimum for the enzyme, the pH optimum for activation, and the pH optimum for whole-cell O2- production are all 7.5. Enzyme activity is increased if the cells are treated with glucose and cyanide, inhibited in cells treated with 2-deoxyglucose (2-DOG), and requires the presence of calcium for activation. These effects are similar to those found for granulocyte O2- production. Thus, the granulocyte O2- generating enzyme system is located on a fraction enriched for plasma membrane markers, and the kinetics of granulocyte production are directly related to the rate and amount of activation of this enzyme.
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PMID:Activation of the guinea pig granulocyte NAD(P)H-dependent superoxide generating enzyme: localization in a plasma membrane enriched particle and kinetics of activation. 624 12

The activity of adenylate cyclase (Ac), cAMP phosphodiesterase (PDE) and 5'-nucleotidase was studied in plasma membranes from the liver of rat embryo of the 20th day of development normally and after exposure to ionizing radiation. Gamma-irradiation of plasma membranes with doses ranging from 0.1 to 100 kR was shown to inhibit the activity of Ac, this effect being more pronounced during stimulation with higher doses of isoproterenol. The activity of 5'-nucleotidase and PDE remained unchanged up to the dose of 100 kR.
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PMID:[Radiation modulation of the activity of the enzymatic systems in isolated plasma membranes in early ontogeny]. 624 41


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