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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The total membrane-bound ATP hydrolytic activity in human epidermis is due to the activities of at least three differently located enzymes, namely Mg++-activated ATPase, phosphomonoesterase and adenyl cyclase. Cytochemical studies on psoriatic epidermis with various inhibitory and stimulatory substances showed reduced activities of ATPase and phosphomonoesterase, and a lack of sensitivity of adenyl cyclase to specific stimulators such as isoproterenol and glucagon. Since no differences of basal adenyl cyclase activity were observed between normal and psoriatic human skin without stimulation, it seems likely that in psoriasis a latent defect of adenyl cyclase may exist, resulting in a deficient response of this enzyme to regulatory agents. In conclusion, the present study reveals that not a single enzyme but the entire membrane-bound nucleotide metabolism is altered in psoriatic keratinocytes, causing a disturbance of the membrane-bound energy utilization, similar to findings in proliferating tumour cells.
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PMID:Ultrastructural localization and differentiation of membrane-bound ATP utilizing enzymes including adenyl cyclase in normal and psoriatic epidermis. 17 85

The effect of the boiled supernatant on synaptosomal adenyl cyclase activity of rat cerebral cortex was investigated. The boiled supernatant markedly increased the accumulation of cyclic AMP in synaptosomes when added to adenyl cyclase system by a mechanism presumably unrelated to inhibition of cyclic AMP phosphod iesterase or adenosine triphosphatase. Magnesium ion was required for synaptosomal adenyl cyclase activity and its stimulation by the boiled supernatant. The result discerned by doubl reciprocal plots showed an increase in Vmax value of adenyl cyclase by addition of the boiled supernatant without significantly altering the affinity for substrate. The enzyme activity was not stimulated by dopamine, histamine and serotonin in either the absence and presence of the boiled supernatant.
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PMID:The stimulatory effect of the boiled supernatant on cyclic AMP formation in synaptosomes from rat cerebral cortex. 17 9

Sarcolemma consists of plasma and basement membranes and constitutes the real permeability barrier to the heart cell. It is considered to provide high electrical resistance and capacitance to heart cell and its properties are essentially similar to those of the other excitable membranes. Methods are now available for isolating heart sarcolemma with high specific activities of adenylate cyclase, (Na(+)-K(+) ATPase, Ca(++) ATPase, and Mg(++) APTase. These enzymes are considered to play an important role in heart function by regulating ion movements across sarcolemma as well as by providing signals for various metabolic processes. Sarcolemma possesses different hormone and drug receptors and any alteration in its composition could result in abnormal responses of the myocardium. We believe that heart failure is associated with sarcolemmal defects which can be detected by monitoring the activities of different membrane-bound enzymes and other related processes.
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PMID:Heart sarcolemma as a dynamic excitable membrane. 17 91

Morphologically intact plasma membranes from guinea pig ventricles were obtained by exposing isolated cell segments to osmotic shock, followed by extraction of actomyosin in 1 M KC1. These preparations contained approximately 1/6 of the protein and 5-10 percent of the mitochondrial markers present in the original cell preparation. Both adenylate cyclase and (Na++K+)-activated ATPase activities were enriched 3-4 fold. The receptor for epinephrine stimulation of adenylate cyclase was retained. The "basal" ATPase activity of 5-6 mumoles of Pi/mg/hr, measured in 120 mM NaC1 or KC1, was approximately doubled in 100 mM NaC1+20 mM KC1. This increment, the (Na++K+)-activated ATPase, was abolished by 10(-5) M ouabain, the Ki for ouabain being approximately 3x10(-7) M. Adenylate cyclase, which had a basal activity of approximately 0.33 nmole of cyclic AMP produced/min/mg of protein, was significantly stimulated by both l-epinephrine and NaF. Half-maximal stimulation was seen at approximately 5x10(-6) M l-epinephrine. Increasing Ca2+ in the range between 10(-7) and 10(-3) M inhibited basal, l-epinephrine-, and NaF-stimulated adenylate cyclase activities. Basal rates of cyclic AMP production were more sensitive to Ca2+ than was l-epinephrine-stimulated adenylate cyclase activity, so that l-epinephrine stimulation was increased from approximately 60 percent in 0.5 mM ethylene glycol bis (beta-aminoethyl ether) N,N'-tetraacetic acid to approximately 150 percent in 10(-7)M Ca2+ and 400 percent in 10(-5) M Ca2+. The inhibitory effect of Ca2+ on adenylate cyclase activity may represent a negative feedback mechanism by which eelevation of intracellular Ca2+ concentration lowers cellular levels of cyclic AMP and thus reduces Ca2+ influx into the myocardium.
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PMID:Biochemical properties of cardiac sarcolemma: adenylate cyclase and (Na++K+)-activated ATPase. 17 92

Because the mechanism whereby Shigella dysenteriae I enterotoxin induces intestinal secretion is unclear, the effect of this toxin on adenylate cyclase activity in rabbit ileal mucosa was studied under various in vitro and in vivo conditions. Activation of adenylate cyclase by Shigella enterotoxin was observed only when substrate (ATP) concentrations above the Km of adenylate cyclase were employed. These concentrations of ATP are greater than those required to demonstrate activation of adenylate cyclase by cholera toxin. Under optimal assay conditions, doses of Shigella toxin between 5.4 and 900 mug of toxin protein and in vivo incubation times between 6 and 18 hr all increased adenylate cyclase activity by about 100%. Shigella toxin produced significant but highly variable increases in mucosal cyclic AMP concentrations, which were less that the rises seen with a comparable dose of cholera toxin. This variability in cyclic AMP response to Shigella toxin and the disparity between Shigella and cholera toxins' effects on mucosal cyclic AMP are probably the result of the different kinetics of adenylate cyclase activated by these enterotoxins. Mucosal Na-K-ATPase activity was unaffected by Shigella toxin. These observations suggest that alterations in fluid and electrolyte transport induced by Shigella enterotoxin may, in part, be mediated by the adenylate cyclase-cyclic AMP system.
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PMID:Activation of intestinal mucosal adenylate cyclase by Shigella dysenteriae I enterotoxin. 17 69

The subcellular distribution of adenyl cyclase was investigated in small intestinal epithelial cells. Enterocytes were isolated, disrupted and the resulting membranes fractionated by differential and sucrose gradient centrifugation. Separation of luminal (brush border) and contra-luminal (basolateral) plasma membrane was achieved on a discontinuous sucrose gradient. The activity of adenyl cyclase was followed during fractionation in relation to other enzymes, notably those considered as markers for luminal and contraluminal plasma membrane. The luminal membrane was identified by the membrane-bound enzymes sucrase and alkaline phosphatase and the basolateral region by (Na+ + K+)-ATPase. Enrichment of the former two enzymes in purified luminal plasma membrane was 8-fold over cells and that of (Na+ + K+)-ATPase in purified bisolateral plasma membranes was 13-fold. F--activated adenyl cyclase co-purified with (Na+ + K+)-ATPase, suggesting a common localization on the plasma membrane. The distribution of K+-stimulated phosphatase and 5'-nucleotidase also followed (Na+ + K+)-ATPase during fractionation.
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PMID:The surface membrane of the small intestinal epithelial cell. I. Localization of adenyl cyclase. 17 91

Liver plasma membranes (LPM) were isolated from rats fed an essential fatty acid-supplemented diet (+EFA) or from rats fed an essential fatty acid-deficient diet (-EFA). The proportions of linoleate and arachidonate in membrane total fatty acids in the -EFA preparations were one-half or less than the values for the +EFA preparations. Basal, F-, or glucagon-stimulated adenylate cyclase activities were significantly lower in EFA-deficient livers than in nondeficient ones. Addition of GTP significantly enhanced glucagon-stimulated adrenylate cyclase in both groups, but extent of stimulation above basal was greater in EFA-deficient livers. Portal vein injection of glucagon in vivo resulted in significantly higher cAMP formation in +EFA livers than in -EFA livers. When glucagon was used in vitro at 1-1,000 nM, stimulation of adenylate cyclase remained lower in EFA-deficient membranes, but extent of stimulation above basal activity was larger in -EFA membranes than in +EFA. Total Na+, K+ (Mg2+)-ATPase from EFA-depleted LPM exhibited significantly higher values of apparent Km and Vmax-5'-Nucleotidase activity, in contrast, was considerably decreased in EFA-deficient rats. These findings show that, in animals, changes in unsaturated fatty acid composition can affect the properties of membrane-bound enzymes. These alterations could be due to changes in membrane physical properties and/or prostaglandin formation.
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PMID:Effect of essential fatty acid deficiency on activity of liver plasma membrane enzymes in the rat. 18 Mar 55

Adenosine triphosphatase (ATPase) activity in erythrocyte membranes from patients with Duchenne dystrophy was inhibited by ouabain less than in normal individuals in assay systems containing high or low contents of salt. Epinephrine and cyclic adenosine monophosphate increased total ATPase activity in all samples, and epinephrine restored ouabain sensitivity to the Duchenne membranes. Basal adenyl cyclase activity in about twice that of controls. Epinephrine stimulated adenyl cyclase activity of normal membranes two to three times, but did not stimulate the enzyme in Duchenne membranes. These differences may reflect a genetic abnormality of the membrane.
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PMID:Biochemical abnormalities of erythrocyte membranes in Duchenne dystrophy. Adenosine triphosphatase and adenyl cyclase. 18 Sep 37

The purpose of this study was to try to differentiate histochemically between the various enzymes which may catalyze the hydrolysis of ATP in developing rat dental tissues. Freeze cut and freeze dried sections of molar and incisor teeth were incubated in lead capture-based media at pH 5.0, 7.2 or 9.4 with one of the following substrates: beta-glycerophosphate, AMP, ADP, ATP, AMP-PNP and tetrasodium pyrophosphate. To establish the enzymatic nature of the hydrolysis parallel sections were incubated after prior fixation in either formaldehyde or glutaraldehyde. By comparing the enzymatic stainings obtained with the various substrates and at the different pH:s, it was concluded that ATP can be visibly hydrolyzed in rat dental tissues by alkaline phosphatase (stratum intermedium, apical part of maturation ameloblasts, basal part of all ameloblasts, odontoblasts and subodontoblastic layer), specific ATPase (apical and basal parts of secretory ameloblasts) and ATP pyrophosphatase and/or adenylate cyclase (stratum intermedium, odontoblasts). Acid phosphatase, specific ADPase, 5'-nucleotidase, inorganic pyrophosphatase, 3':5'-cyclic-AMP-phosphodiesterase and adenylate kinase on the other hand, seem not to be engaged in the ATP hydrolysis to such a degree as to complicate the interpretation of the histochemical staining. The alkaline phosphatase part of the ATP hydrolysis appeared to be rather insensitive to aldehyde fixation, while the hydrolysis effected by specific ATPase and ATP pyrophosphatase and/or adenylate cyclase was extinguished after fixation with formaldehyde for 4 h or glutaraldehyde for 10 min.
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PMID:Adenosine triphosphate hydrolysis in rat dental tissues. A histochemical study to differentiate the enzymes involved. 18 60

Changes in adenosine triphosphatase (ATPase) activity of the peripheral blood leukocytes were investigated in patients with bronchial asthma. Estimation of the leukocyte Mg++- and Ca++- dependent ATPases was carried out according to Hadden's method, incubating ATP with the membrane fraction of the leukocyte. The leukocyte ATPase activity was significantly elevated among asthmatic patients compared with control subjects. This elevated ATPase was seen in all asthmatics irrespective of acute attacks or the drug treatment. There was no clear correlation between the activity of ATPase and the percentage of leukocytes, neutrophils and eosinophils. There was no relationship between ATPase activity and adenyl cyclase activity of the same leukocytes from asthmatic patients.
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PMID:Leukocyte adenosine triphosphatase activity in human bronchial asthma. 18 9


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