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)

Whole sheets of plasma membrane, each with their attached flagellum, were purified from Trypanosoma brucei. The method devised for their isolation included a new technique of cell breakage that used a combination of osmotic stress followed by mechanical sheer and avoided the problem of extreme vesiculation as well as the trapping of organelles in cell 'ghosts'. The purified membranes all contained the pellicular microtubular array. The antigenic surface coat was completely released from the plasma membrane during the isolation procedure. The membranes had a very high cholesterol/phospholipid ratio (1.54). A large proportion (42%) of the cellular DNA was recovered in the plasma-membrane fraction unless a step involving deoxyribonuclease treatment, which decreased the DNA content to less than 13%, was included before secrose-density gradient centrifugation. This step also aided the separation of plasma membranes from other cellular components. The ouabain-sensitive Na+ + K+-stimulated adenosine triphosphatase and adenylate cyclase co-purified with the plasma membranes. Although 5'-nucleotidase was thought to be a plasma-membrane component, it was easily detached from the membrane. The purified membranes were essentially free of L-alanine-alpha-oxoglutarate aminotransferase, L-asparte-alpha-oxoglutarate aminotransferase, malate dehydrogenase, oligomycin-sensitive adenosine triphosphatase, glucose 6-phosphatase, Mg2+-stimulated p-nitrophenyl phosphatase and catalase.
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PMID:The isolation and partial characterization of the plasma membrane from Trypanosoma brucei. 48 94

The influence of an oxygen-free radical scavenger, Epurox (containing superoxide dismutase, catalase and mannitol) on E-rosette forming cells (E-RFC) obtained from 40 healthy subjects, was studied using a standard method. The preincubation of lymphocytes with Epurox increased the E-rosette forming in 80% of the subjects. The mean E-rosette count after preincubation with Epurox (64.17 +/- 6.95) was greater (p less than 0.01) as compared with that obtained without scavenger addition. The stimulating effect of Epurox may be due to the inhibition of cAMP synthesis. This assumption is supported by our study regarding the antagonistic effect of Epurox on E-rosette inhibition induced by histamine, a powerful stimulator of adenylate cyclase.
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PMID:Immunostimulating effect of an oxygen-free radical scavenger on E-rosette forming cells. 209 97

In Saccharomyces cerevisiae, lack of nutrients triggers a pleiotropic response characterized by accumulation of storage carbohydrates, early G1 arrest, and sporulation of a/alpha diploids. This response is thought to be mediated by RAS proteins, adenylate cyclase, and cyclic AMP (cAMP)-dependent protein kinases. This study shows that expression of the S. cerevisiae gene coding for a cytoplasmic catalase T (CTT1) is controlled by this pathway: it is regulated by the availability of nutrients. Lack of a nitrogen, sulfur, or phosphorus source causes a high-level expression of the gene. Studies with strains with mutations in the RAS-cAMP pathway and supplementation of a rca1 mutant with cAMP show that CTT1 expression is under negative control by a cAMP-dependent protein kinase and that nutrient control of CTT1 gene expression is mediated by this pathway. Strains containing a CTT1-Escherichia coli lacZ fusion gene have been used to isolate mutants with mutations in the pathway. Mutants characterized in this investigation fall into five complementation groups. Both cdc25 and ras2 alleles were identified among these mutants.
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PMID:Control of Saccharomyces cerevisiae catalase T gene (CTT1) expression by nutrient supply via the RAS-cyclic AMP pathway. 254 66

Variations in catalase, glutathione peroxidase (GP) and adenylate cyclase (AC) activity in murine erythroleukemic (MEL) cells were studied during multiplication and dimethylsulfoxide (DMSO)-induced differentiation. The results demonstrated that, although DMSO favors the incorporation of 3H-thymidine into DNA of treated cells, it slows down cell multiplication. Increased incorporation was also observed in superoxide dismutase (SOD)-treated cells. DMSO also determined an early and significant drop in AC activity and a late fall in catalase activity, whereas there was no significant variation in GP activity in parallel with the decreased cell multiplication that accompanied cell differentiation. We hypothesize that DMSO and SOD favor 3H-thymidine incorporation by neutralizing the reactive forms of oxygen and that the reduction in catalase and AC activity is closely related to the mitotic activity of MEL cells.
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PMID:Effects of dimethylsulfoxide on Friend erythroleukemic cell proliferation and on the activity of enzymes involved in this process. 273 3

The generation of superoxide radicals from xanthine oxidase-hypoxanthine in a particulate fraction of gerbil cerebral cortex influenced the activity of the synaptic enzyme adenylate cyclase, as well as Mn2+- and Na+,K+-sensitive forms of ATPase. Low concentrations of xanthine oxidase actually elevated the sensitivity of adenylate cyclase to GTP, GTP + norepinephrine (NE), and forskolin but not significantly to Mn2+. Higher levels of xanthine oxidase elicited a marked inhibition of these responses. The stimulation of adenylate cyclase mechanisms requiring GTP (GTP, forskolin, and NE) was more susceptible than was Mn2+, suggesting that the guanine nucleotide stimulatory protein was more vulnerable to free radical attack than the catalytic site of adenylate cyclase. Superoxide dismutase (SOD), but not catalase, partially protected the forskolin-sensitive enzyme from the action of xanthine oxidase-hypoxanthine. A combination of SOD plus catalase preserved enzyme responses to forskolin. In comparison, additions of SOD plus mannitol or catalase plus flunarizine were less effective. The sensitivity of the particulate ATPase to Mn2+ was more labile to the consequence of superoxide formation than Na+, K+ -ATPase. In this regard the Ca2+,Mg2+ sensitivity of the enzyme was reduced only to a marginal extent. The findings might be analogous to in vivo data in which cerebral adenylate cyclase and Na+, K+-ATPase are damaged following postischemic reperfusion in gerbils, a process thought to be mediated by free radicals.
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PMID:Free radicals generated by xanthine oxidase-hypoxanthine damage adenylate cyclase and ATPase in gerbil cerebral cortex. 285 Apr 58

A series of six beta-adrenergic blocking drugs including propranolol, bufetolol, bunitrolol, pindolol, labetalol and acebutolol were examined for effects on adenylate cyclase, guanylate cyclase and calmodulin-dependent phosphodiesterase from heart. The adrenergic blocking agents had no apparent effects on basal activities of adenylate cyclase, guanylate cyclase and phosphodiesterase. The drugs blocked the enhancement of adenylate cyclase activity by isoproterenol, but not by guanine nucleotide or fluoride. The inhibitory effects of beta-antagonists were overcome by sufficiently large doses of isoproterenol. Sodium azide specifically required catalase whereas NaNO2 required cysteine to activate myocardial guanylate cyclase. Among beta-adrenergic blocking drugs tested, both pindolol and acebutolol inhibited the stimulation of guanylate cyclase by NaNo2 or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). However, other beta-blocking drugs did not significantly affect the activation by NaN3, NaNO2 and MNNG. Several beta-antagonists, such as labetalol, bunitrolol, pindolol and acebutolol were also effective in blocking the activation of phosphodiesterase by calmodulin. The inhibitory effects of beta-adrenergic blocking drugs, i.e. pindolol and acebutolol upon either nitroso compound-stimulated guanylate cyclase or calmodulin-activated phosphodiesterase display little correlation with their potency as beta-adrenergic blocking agents. These data suggest that beta-antagonists may have another site of action which is not directly related to the control of catecholamine metabolism.
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PMID:Different effects of various beta-adrenoceptor antagonists on adenylate cyclase, guanylate cyclase and calmodulin-dependent phosphodiesterase in heart. 286 Sep 6

1. Two directly-acting stimulants of soluble guanylate cyclase, glyceryl trinitrate (0.1 microM) and sodium azide (10 microM), and a receptor-mediated stimulant of particulate guanylate cyclase, atriopeptin II (10 nM), each elevated the cyclic GMP content of primary cultures of pig aortic endothelial cells without affecting the cyclic AMP content. 2. Two receptor-mediated stimulants of adenylate cyclase, glucagon (1 microM) and isoprenaline (10 microM), had no effect on the cyclic AMP or cyclic GMP content of these cells, but the directly acting stimulant, forskolin (30 microM), induced a small increase in cyclic AMP content. 3. Three agents that release endothelium-derived relaxing factor (EDRF); bradykinin (0.1 microM), ATP (10 microM) and ionophore A23187 (0.1 microM), each markedly elevated the cyclic GMP content of pig aortic endothelial cells, but acetylcholine (1 microM) had no effect. None of these agents had any effect on cyclic AMP content. 4. Two agents that potentiate the actions of EDRF; M & B 22948 (100 microM) and superoxide dismutase (30 units ml-1), each elevated the cyclic GMP content of pig aortic endothelial cells without affecting the cyclic AMP content. Pretreating cells with catalase (100 units ml-1) did not affect the rise in cyclic GMP content induced by superoxide dismutase (30 units ml-1). 5. Pretreatment of pig aortic endothelial cells with haemoglobin (10 microM) reduced the resting content of cyclic GMP and blocked the increase in cyclic GMP content induced by glyceryl trinitrate (0.1 microM), sodium azide (10 microM), bradykinin (0.1 microM), ATP (10 microM), ionophore A23187 (0.1 microM), M & B 22948 (100 microM) and superoxide dismutase (30 units ml-1), but not that induced by atriopeptin II (10 nM). 6. Pretreatment of pig aortic endothelial cells with an inhibitor of soluble guanylate cyclase, methylene blue (20 microM), had no effect on the resting content of cyclic GMP. Methylene blue (20 microM) blocked the increase in cyclic GMP content induced by glyceryl trinitrate (0.1 microM), M & B22948 (100 microM) and bradykinin (0.1 microM), but not that induced by atriopeptin II (10 nM). 7. The data show that soluble guanylate cyclase, particulate guanylate cyclase and adenylate cyclase are present in pig aortic endothelial cells. They further suggest that EDRF, produced spontaneously or in response to vasoactive agents, elevates endothelial cyclic GMP content by stimulating soluble guanylate cyclase. It is possible that this may serve as a feedback loop by which the endothelial cell modulates EDRF production.
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PMID:Endothelium-derived relaxing factor and atriopeptin II elevate cyclic GMP levels in pig aortic endothelial cells. 289 77

UVB irradiation augmented the beta-adrenergic adenylate cyclase response of pig skin epidermis in vitro. The effect was observed 2-4 h following the irradiation and lasted at least for 48 h. There was no significant difference in cyclic AMP phosphodiesterase activity between control and UVB-irradiated epidermis at lower irradiation dose (150 mJ/cm2), which is the dose of the most marked beta-adrenergic augmentation effect. The augmentation effect was specific to the beta-adrenergic system; adenosine and histamine adenylate cyclase responses were unchanged or decreased depending on the irradiation dose. Histologically, marked sunburn-cell formation was observed following the UVB irradiation. It has been suggested that oxygen intermediates generated by ultraviolet radiation participate in sunburn-cell formation. The addition of superoxide dismutase (SOD) in the incubation medium significantly inhibited sunburn-cell formation. On the other hand, the beta-adrenergic augmentation effect was not affected by the addition of SOD. Other scavengers of oxygen intermediates (catalase, catalase + SOD, xanthine, or mannitol) did not inhibit the UVB-induced beta-adrenergic augmentation effect. Further, superoxide-anion generating systems (hypoxanthine-xanthine oxidase system and acetaldehyde-xanthine oxidase system) revealed no stimulatory effect on the beta-adrenergic response of epidermis. These results indicate that (a) the UVB-induced beta-adrenergic augmentation effect is inherent to skin and does not depend on systemic factors such as inflammatory infiltrates following UVB irradiation; (b) in contrast to sunburn-cell formation, induction of the beta-adrenergic adenylate cyclase response is not directly associated with oxygen intermediates generated by UVB irradiation.
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PMID:Effects of UVB irradiation on epidermal adenylate cyclase responses in vitro: its relation to sunburn cell formation. 289 32

1. The possible interactions between prostacyclin and endothelium-derived relaxing factor were examined, in isolated coronary arteries of the pig treated with indomethacin (10(-5) M). 2. In organ chamber experiments, prostacyclin caused relaxations, which were potentiated in the presence of the endothelium; the potentiation was abolished by oxyhaemoglobin. 3. In bioassay experiments, prostacyclin caused minimal relaxations of bioassay rings without endothelium; these relaxations were potentiated when the bioassay ring was exposed to basally-released endothelium-derived relaxing factor (interaction between prostacyclin and basal endothelium-derived relaxing factor) and further augmented when the endothelial cells were exposed to the prostanoid (stimulated release of endothelium-derived relaxing factor). The endothelium-dependent, but not the direct effects of prostacyclin were augmented by superoxide dismutase plus catalase and abolished by oxyhaemoglobin. 4. Forskolin, a direct activator of adenylate cyclase, caused relaxations of rings without endothelium, which were augmented by the presence of the endothelium. 5. The relaxations induced by prostacyclin or forskolin also had an endothelium-dependent component in basilar and femoral arteries and in jugular veins of the pig. 6. The endothelium-dependent actions of prostacyclin probably reflect activation of adenylate cyclase.
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PMID:Prostacyclin releases endothelium-derived relaxing factor and potentiates its action in coronary arteries of the pig. 306 55

Distribution of adenylate cyclase and guanylate cyclase activities in neuronal perikarya and glial cells separated from rat brain, and cellular differences in activation between of adenylate cyclase by NaF and of guanylate cyclase by NaN3 have been studied. Adenylate cyclase activity was higher in the glial cells than in the neuronal fraction, while guanylate cyclase activity was equally detected in both cell fractions. Adenylate cyclase was mainly derived from the particulate fraction of both brain cell homogenates, whereas the major portion of guanylate cyclase activity was found in their soluble rather than in the particulate fractions. Although bulk-separated neurons and glial cells almost failed to change intracellular cyclic nucleotide levels in response to some putative neurotransmitters, activation of adenylate cyclase by NaF was found to be greater in neuronal than in glial cell fractions, and was observed more clearly in the soluble than in the particulate fractions. Sodium azide greatly increased guanylate cyclase in the particulate fraction, but did not affect it considerably in the soluble one. Addition of catalase to the reaction mixture together with NaN3 further stimulated guanylate cyclase both int he soluble and the particulate fractions. These results suggest that adenylate cyclase and guanylate cyclase without intimate coupling to the transmitter-receptor system, but with activation by NaF or NaN3, may be distributed ubiquitously in the cells separated from rat cerebral cortex.
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PMID:Distribution and different activation of adenylate cyclase by NaF and of guanylate cyclase by NaN3 in neuronal and glial cells separated from rat cerebral cortex. 611 97


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