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)

It has been shown that the activity of Ca(2+)-ATPase increases during development. Epinephrine in vivo increases the activity of Ca(2+)-ATPase in chick skeletal muscles. The effect of hormone is lacking at embryonic stages of development and appears only before hatching. In the presence of exogenous protein kinase, cAMP also increases the activity of the enzyme, this effect being observed also in embryonic muscles. Lack of effect of epinephrine on Ca(2+)-ATPase in embryonic muscles is associated with non-reactivity of their adenylate cyclase to catecholamines. Ca(2+)-ATPase itself already at embryonic period is ready to react to cAMP. It is concluded that Ca(2+)-ATPase of sarcoplasmic reticulum is one of the sites of action of catecholamines on calcium metabolism in muscle cell and that this action is realized via the system adenylate cyclase-cAMP-protein kinase.
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PMID:[The effect of catecholamines on the Ca2(+)-adenosinetriphosphatase of the sarcoplasmic reticulum in the skeletal muscles in chicken ontogeny]. 9 34

The adenylate cyclase activity of a particulate preparation of rat cerebral cortex is comprised of two contributing components, only one of which requires a CDR for activity. The CDR-dependent component was inhibited by high ratios of Mg2+ to Ca2+, responded in a biphasic manner (activation then inhibition) to increasing free Ca2+ concentrations, was inhibited by 0.1 to 0.4 mM chlorpromazine, and was activated by 1 to 100 micrometer cocaine. This enzyme form, which represented approximately 80% of tge basal activity of a cortex homogenate, was stable during pretreatment of homogenates at 45 degrees C but was completely deactivated by the removal of CDR during the preparation of the particulate fraction. Adenylate cyclase activity that did not depend on CDR was unaffected by the removal of CDR during the preparation of the particulate fraction, had elevated activity at high ratios of Mg2+ to Ca2+, was inhibited by Ca2+, was unaffected by 0.1 to 0.4 mM chlorpromazine and was slightly inhibited by 1 to 100 micrometer cocaine, and was not stable during pretreatment of homogenates at 45 degrees. The CDR-dependent component of adenylate cyclase activity was activated by 5 mM NaF to varying degrees depending on the concentration of CDR present in the assay. NaF decreased the concentration of CDR required to produce half-maximal velocity obtained at optimal concentrations of CDR. Activation by NaF required the presence of Ca2+ and was immediately and completely reversed by EGTA. In contrast, the component that did not respond to CDR was activated four- to fivefold by NaF. This activation was not influenced by Ca2+ or CDR and was not reversed by EGTA. The observed effects of effects of divalent cations on the CDR-dependent enzyme are discussed in relation to the cation-binding properties of CDR. The relationship of the CDR-dependent form of adenylate cyclase to other forms of this enzyme remains to be determined.
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PMID:Calcium-dependent regulation of brain adenylate cyclase. 9 69

The sarcolemma fraction with a considerable adenylate cyclase activity sensitive to adrenalin is isolated from the rabbit skeletal muscles. Some its properties are established: pH-optimum of the activity, stability in storage and resistance to the effect of different pH and temperature. Acetylcholine and ruthenium red do not affect the adenylate cyclase activity of the sarcolemma. EGTA activates and Ca2+ inhibits it having no effect on sensitivity to adrenalin.
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PMID:[Properties of adenylate cyclase of rabbit skeletal muscle sarcolemma]. 10 69

Adenylate cyclase was assayed in a sonicated preparation of silkworm pupal fat body. The adenylate cyclase was found mostly in the particulate fraction. The activity depended upon either Mg2+ or Mn2+, and the degree of stimulation by Mn2+ was 2 times greater than that by Mg2+ compared at the saturating concentrations. In the presence of Mg2+, the enzyme was inhibited by both EGTA and high concentrations of Ca2+, showing biphasical response to Ca2+. The enzyme was stimulated several-fold by NaF. The enzyme exhibited typical Michaelis-Menten kinetics and Km values were 0.13 mM for MgATP and 0.086 mM for MnATP.
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PMID:Adenylate cyclase in silkworm. Properties of the enzyme in pupal fat body. 10 81

An adenylate cyclase present in the brain of the moth Mamestra configurata Wlk. that is stimulated selectively by low (micromolar) concentrations of octopamine has been characterized with respect to several properties. The optimum pH, optimum ATP:Mg2+ ratio, the concentration of ATP required for half-maximal and maximal reaction velocity, metal ion specificity, effect of NaF, and effects of GTP and 5'-guanylylimidodiphosphate were in general similar to those of catecholamine-sensitive adenylate cyclases from various regions of mammalian brain. However, ethylene glycol bis-(beta-aminoethyl ether)-N,N-tetraacetic acid (EGTA), a calcium chelator, stimulated both basal and octopamine-sensitive enzyme activity in the insect brain, whereas in mammalian brain EGTA is usually observed to inhibit basal activity but not catecholamine-stimulated activity. Adenylate cyclase activity of the 47,000 g particulate fraction of the insect brain was almost undetectable in the absence of added GTP. Addition of saturating concentrations (100 micrometer) of GTP to the particles restored about 30% of the basal and octopamine-sensitive enzyme activity present in the homogenate. Addition of 100,000 g supernatant to the particles doubled both basal and octopamine-sensitive enzyme activity in the presence of saturating concentrations of GTP, indicating that in addition to GTP, a cytosolic factor(s) is necessary for enhanced adenylate cyclase activity.
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PMID:Characterization of an octopamine-sensitive adenylate cyclase from insect brain (Mamestra configurata Wlk.). 10 6

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

1. The prior addition of non-aggregating concentrations of the divalent cation ionophore, A-23187, causes human platelets to aggregate in response to a subsequent addition of the 2',3'-dialdehyde and 2',3'-dialcohol derivatives of ADP (oADP and or ADP). Previous studies [Pearce et al. (1978) Eur. J. Biochem. 88, 543--555] have shown that these derivatives act as partial agonists at the platelet ADP receptor inducing only the transition from discoid to globular morphology ('shape change'). A secretion response is also observed on addition of a low concentration of ionophore A-23187 prior to orADP. These responses are not observed if ionophore A-23187 is added prior to the 2',3'-dialdehyde and 2',3'-dialcohol derivatives of ATP (oATP and or ATP) and are markedly inhibited by prior addition of the ADP antagonist, adenosine 5'-[beta, gamma-methylene]triphosphate. 2. The aggregation response to oADP in the presence of ionophore A-23187 is reduced but not eliminated by addition of 3 mM EGTA when studies are performed in heparinised platelet-rich plasma. Additions of 3 mM EGTA in citrated platelet-rich plasma, or of 4 mM EDTA in either system completely inhibits this response. Inhibitors which are reported to elevate the intracellular concentration of adenosine 3':5'-monophosphate (cyclic AMP) or to prevent Ca2+ movement also inhibit the aggregation response to oADP which is observed in the presence of ionophore A-23187. 3. Prior addition of inhibitors of adenylate cyclase fails to cause an aggregation response to subsequent addition of oADP or orADP. Certain of these inhibitors enhance and prolong the shape change response to oADP or orADP but only at concentrations an order of magnitude in excess of those required to antagonise inhibition by agents such as prostaglandin E1, which act by increasing the concentration of cyclic AMP. 4. The concentration of prostaglandin E1, adenosine or papaverine required to inhibit shape change induced by oADP is one to two orders of magnitude lower than that required to inhibit shape change induced by ADP. 5. Prior addition of oADP decreases the lag phase in the response of human platelets to arachidonate while also increasing the concentration required to observe half-maximal response, and causing a decrease in the extent of the response. Prior addition of oATP also diminishes the extent of this response and increases the concentration of arachidonate required but has no effect on the lag phase. 6. The data suggest that oADP and orADP are capable only of acting as partial agonists at the ADP receptor because of a defective ability to increase cytosolic Ca2+ concentration. The defect is rectified by the presence of low concentrations of ionophore A-23187, which promotes mobilisation of Ca2+ from an intracellular store. The results do not appear consistent with the thesis that a decrease in platelet cyclic AMP is an initiating event in aggregation induced by ADP, but do support a model which implicates cyclic AMP in depletion of cytosolic Ca2+.
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PMID:Factors influencing the response of human blood platelets to analogues of ADP which may act as partial agonists at the ADP receptor. 11 May 86

A plasma membrane preparation purified from guinea pig ventricles without the use of high concentrations of detergents or structure-disrupting salts was used to compare the mechanisms of controlling sodium, potassium-activated adenosinetriphosphatase (Na, K-ATPase) and adenylate cyclase activities. The basal ATPase activity of 4-6 mu moles P1/hour mg-1 protein, measured in 120 mM NaC1 or KC1, was approximately doubled in 100 mM NaC1 plus 20 mM KC1. This increment, the Na, K-ATPase, was abolished by 10-5M ouabain, the K1 for ouabain being approximately 3 X 10-7M. 1-Epinephrine had no effect on Na, K-ATPase, but NaF was inhibitory. Adenylate cyclase, which had a basal activity of approximately 50% by NaC1 or KC1 alone at concentrations up to 0.2M. There was no additional stimulation of adenylate cyclase activity when na+ K+ included together. Both 1-epinephrine and NaF cause significant stimulation of adenylate cyclase, but neither basal nor activated cyclic AMP PRODUCTION WAS INFLUENCED BY OUABAIN. Half-maximal stimulation was seen at approximately 5 X 10-6M 1-epinephrine. Both the catecholamine and NaF increased the V-max ofcardiac plasma membrane adenylate cyclase without significantly influencing Km. Increasing Ca2+ in the range between 10-7 and 10-3M inhibited basal, 1-epinephrine-stimulated, and NaF-stimulated activities. Basal rates of cyclic AMP production were more sensitive to Ca2+ than was 1-epinephrine stimulation was increased from approximately 60% in 0.5 mM EGTA to approximately 150% in 10-7M Ca2+ and 400% in 10-5M Ca2+. The inhibitory effect of Ca2+ on adenylate cyclase activity may represent a negative feed back mechanism by which elevation of intracellular Ca2+ concentration lowers cellular levels of cyclic AMP and thus reduces Ca2+ influx into the myocardium.
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PMID:Control of cardiac sarcolemmal adenylate cyclase and sodium, potassium-activated adenosinetriphosphatase activities. 12 80

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

Sarcolemmal Ca++-ATPase, Mg++-ATPase, and (Na+-K+)-ATPase activities were increased in late stages of heart failure in myopathic hamsters (BIO 14.6) without any changes in the adenylate cyclase activity. On the other hand, these hamsters at early and moderate stages of heart failure showed depressions in mitochondrial calcium binding and uptake and microsomal calcium binding. Sarcolemmal (Na+-K+)-ATPase was decreased in failing hearts because of substrate lack, oxygen lack, and perfusion with Ca++-free, Na+-free, or K+-free medium. Both Mg++-ATPase and Ca++-ATPase activities of sarcolemma did not change on perfusing the hearts with substrate-free, hypoxic, Na+-free, or K+-free medium. Adenylate cyclase activity decreased on substrate-free or Ca++-free perfusion. Intracellular calcium overload produced by perfusing the hearts with medium containing calcium after Ca++-free perfusion was associated with decrease in all the sarcolemmal-bound enzyme activities. All types of failing hearts employed in this study showed a dramatic shift in the electrolyte composition. Failure of the cardiac muscle to generate contractile force on treatment with trypsin was associated with defects in the functions of sarcolemma, mitochondria, and sarcoplasmic reticulum, whereas such an effect on treatment with phospholipase C was limited to alterations in the activities of sarcolemma. The data suggest that abnormality at the level of sarcolemma plays an important role in the pathogenesis of heart dysfunction; however, the degree and direction of alterations in the sarcolemmal functions seem to be dependent upon the type of heart failure.
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PMID:Role of sarcolemmal changes in cardiac pathophysiology. 13 Jun 63


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