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)

Two highly lead-sensitive ATPases, Na+,K+-ATPase and adenylate cyclase, can be demonstrated cytochemically by the lead precipitation technique in briefly prefixed tissue, provided that the free Pb2+ concentration in the incubation medium is kept below 0.1 mM by a heavy metal chelator. Under conditions suitable for Na+,K+-ATPase activity precipitation of final reaction product (lead phosphate) at the sarcolemma of cardiac muscle is abolished by 0.1-1mM ouabain. In contrast, reaction product deposition at the intramuscular part of the plasma membrane and at intracellular sites is not noticeably affected by the glycoside. These findings indicate either that the sarcolemma is the exclusive location of Na+,K+-ATPase in cardiac muscle or that the presence of the enzyme at other loci is masked by active Na+,K+-independent, ouabain resistant ATPases. Under conditions favoring adenylate cyclase activity, precipitation by Pb2+ of orthophosphate derived, with the help of added cyclic nucleotide phosphodiesterase and 5'-nucleotidase, from cyclic AMP formed from adenylyl imidodiphosphate (AMP-PNP) is seen after prolonged incubation in myocardial cells along the entire course of the plasma membrane and also at the transverse tubules and is particularly intense at the tight junction regions of the intercalated disks. Ouabain has no effect on these reactions. Reaction product deposition is also observed at the sarcolemma in red skeletal muscle and at the terminal cisternae of the sarcoplasmic reticulum in white skeletal muscle, where the reaction is intensified by adrenaline. Sarcoplasmic reticulum of cardiac and of red skeletal muscle exhibits only relatively weak staining attributable to cyclic AMP formation. These observations are in agreement with the results of tissue fractionation studies according to which the plasma membrane is the chief site of adenylate cyclase in heart and in red, but not white skeletal muscle.
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PMID:Cytochemical studies on sarcolemma: Na+, K+-adenosine triphosphatase and adenylate cyclase. 13 Jun 56

Phosphodiesterase activator protein and troponin-C have been purified from rat testis and rabbit skeletal muscle, respectively. The two proteins appear to be structurally distinct since the activator protein migrates faster than troponin-C on sodium dodecyl sulfate-polyacrylamide gels. Each of the calcium-binding proteins will, however, substitute for the other in their respective biological systems. Testis activator protein forms a complex with rabbit muscle troponin subunits TnI and TnT soluble in low salt. This hybrid complex (AIT) can regulate rabbit skeletal muscle actomyosin ATPase activity. AIT regulation, although influenced by free Aa2+ levels, is distinct from that of native troponin. Likewise, muscle troponin-C can substitute for activator protein in the stimulation of cyclic nucleotide phosphodiesterase. Troponin-C will fully stimulate phosphodiesterase although its affinity is 600-fold lower than that of activator protein. Ca2+ regulation studies demonstrate that both proteins require micormolar levels of free Ca2+ to induce phosphodiesterase activation. Activator protein requires 1.2 x 10(6) M and troponin-C, 1.9 X 10(6) M free Ca2+ for half-maximal stimulation of phosphodiesterase. The biological cross-reactivity of these proteins supports the sequence homology recently reported by Watterson et al. (Watterson, D.M., Harrelson, W.G., Keller, P.M., Sharief, F., and Vanaman, T.C. (1976) J.Biol. Chem. 251, 4501-4513). In addition, this preliminary study suggests that this nonmuscle troponin-C-like protein potentially may function in other Ca2+-regulated cellular events in addition to its moculation of cyclic nucleotide levels.
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PMID:Biological cross-reactivity of rat testis phosphodiesterase activator protein and rabbit skeletal muscle troponin-C. 19 60

When cyclic nucleotide phosphodiesterase was purified from isolated smooth muscle layer of human aorta by DEAE-cellulose column chromatography, separated cyclic GMP phosphodiesterase activity was markedly stimulated in the presence of 10-20 micrometer of Ca2+ by a protein modulator which has similar physicochemical properties to troponin C. Synthetic compound, N-(6-aminohexl)-5-chloro-1-naphthalensulfonamide, which produced relaxations of arteries contracted by prostaglandin F2alpha or KCl was found to inhibit selectively this Ca2+-dependent cyclic GMP phosphodiesterase. This compound produced inhibition of superprecipitation of myosin B system obtained from mouse skeletal muscle and also inhibited adenosine triphosphatase activity of myosin B. Our data suggest that calcium is involved through a protein modulator in cyclic nucleotide metabolism of vascular smooth muscle and that the calcium-dependent protein modulator probably participates in the regulation of contractile response of vascular smooth muscle by affecting actomyosin ATPase activity.
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PMID:Involvement of calcium in cyclic nucleotide metabolism in human vascular smooth muscle. 20 83

The recently discovered heat-stable inhibitor protein of the Ca2+-activated cyclic nucleotide phosphodiesterase (Sharma, R. K., Wirch, E. & Warg, J. H. (1978) J. Biol. Chem., in press) has been purified 238 214-fold from bovine brain extract using an affinity column of the modulator protein--Sepharose 4B conjugate. The purified sample appears to be homogeneous as judged by sodium dodecyl sulphate (SDS) gel electrophoresis. The protein band has a mobility corresponding to that of a polypeptide of molecular weight 68 000. Since the heat-stable inhibitor protein has a molecular weight of 70 000 under nondenaturing conditions, it suggests that it is a monomeric protein. The protein has no inhibitory activity toward the cAMP-dependent protein kinase or protein phosphatase. The purified sample has been tested for various enzyme activities which include ATPase, GTPase, cAMP phosphodiesterase, cGMP phosphodiesterase, 5'-nucleotidase, and protein kinase. None of these activities are exhibited by the purified sample.
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PMID:Purification of the heat-stable inhibitor protein of the Ca2+-activated cyclic nucleotide phosphodiesterase by affinity chromatography. 20 31

The hormone serotonin (5-hydroxytryptamine) has been implicated as the cause of the diarrhea seen in many patients with the carcinoid syndrome. To determine whether serotonin is an intestinal secretagogue, the effect of serotonin on intestinal water and electrolyte transport was evaluated in the rabbit. Two weeks of daily subcutaneous injection of serotonin suspended in oil resulted in a blood serotonin level elevated to twice that of controls. Intestinal transport was studied in vivo by a perfusion technique. Serotonin treatment resulted in ileal secretion and decreased mid-jejunal absorption of water and electrolytes but did not effect water absorption in the proximal jejunum or colon. Intestinal absorption of D-glucose and the amino acid L-tryptophan and glucose-dependent water and electrolyte absorption were normal in serotonin-treated animals. Serotonin-induced ileal secretion was reversed by methysergide, a peripheral antagonist of serotonin action. No alterations in intestinal histology or permeability occurred in serotonin-treated animals. Serotonin-induced intestinal secretion was not associated with alterations in the activities of intestinal mucosal adenylate cyclase, cyclic nucleotide phosphodiesterase, or Na-K-ATPase.
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PMID:Effect of serotonin treatment on intestinal transport in the rabbit. 83 7

An acidic calcium-binding protein was isolated from the soluble fraction of the homogenate of ox neurohypophyses. The protein has a molecular weight of 35 000 and a subunit weight of 15 000. The purification procedure involved ammonium sulphate fractionation, DEAE-cellulose chromatography and gel filtration on Sephadex G-100 and Sephadex G-50. Conventional and sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated it to be a protein distinct from the S-100 protein and the soluble hormone-binding proteins (neurophysins) abundant in the neurohypophysis. This appears to be the only Ca2+-binding protein in the soluble part of the homogenate, with an apparent Kdiss for Ca2+ of 1.1 X 10(-5) M (at 22 degrees C) and a binding capacity of 2 mol of calcium per mol of protein. Two different Ca2+-binding proteins of molecular weights 16 500 and 68 000, respectively, were identified in the sodium-deoxycholate-soluble proteins from an ox neurohypophysial microsome fraction. One of them (the former) has been isolated in high purity by DEAE-cellulose chromatography and gel filtration on Sephadex G-200. This protein binds 4 mol of calcium per mol of protein with an apparent Kdiss of 1.0 X 10(-5) M (at 22 degrees C). The sodium-deoxycholate-insoluble proteins from the microsomal fraction also have Ca2+-binding components. The soluble Ca2+-binding protein has properties similar to and may be identical to Ca2+-binding proteins which have been isolated from bovine brain and have been demonstrated to be modulators of brain cyclic nucleotide phosphodiesterase and of actinomyosin ATPase. It also resembles Ca2+-binding proteins isolated from bovine adrenals and the electroplax from electrophorus electricus.
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PMID:Isolation and purification of calcium-binding proteins from bovine neurohypophyses. 87 62

A procedure is described for the isolation of synaptic membrane fragments that retain such functionally important proteins as acetylcholine receptors, acetylcholinesterase, 3',5'-cyclic nucleotide phosphodiesterase, and (Na+ + K+)-ATPase. The method is based on the observation, made in brain slices, that junctional membranes are more resistant to phospholipase A2 attack than mitochondrial or plasma membranes. Hydrolysis by phospholipase A2 was controlled by addition of fatty acid-free bovine serum albumin. The membrane fraction obtained represents approximately a 15-fold enrichment of the postsynaptic marker proteins muscarinic and nicotinic acetylcholine receptor and 3',5'-cyclic nucleotide phosphodiesterase over an ordinary synaptic plasma membrane preparation, and is devoid of mitochondrial and microsomal contaminations. The membranes appear on the electron micrographs as rigid fragments (average length 2500-4000A), which do not form vesicles.
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PMID:Isolation of a synaptic membrane fraction enriched in cholinergic receptors by controlled phospholipase A2 hydrolysis of synaptic membranes. 125 6

Purified porcine erythrocyte membrane Ca(2+)-ATPase and 3':5'-cyclic nucleotide phosphodiesterase were stimulated in a dose-dependent, saturable manner with the vitamin D-dependent calcium binding protein from rat kidney, calbindin-D28k (CaBP-D28k). The concentration of CaBP-D28k required for half-maximal activation (K0.5 act.) of the Ca(2+)-ATPase was 28 nM compared to 2.2 nM for calmodulin (CaM), with maximal activation equivalent upon addition of either excess CaM or CaBP-D28k. 3':5'-Cyclic nucleotide phosphodiesterase (PDE) also showed equivalent maximum saturable activation by calbindin (K0.5 act. = 90 nM) or calmodulin (K0.5 act. = 1.2 nM). CaBP-D28k was shown to effectively compete with CaM-Sepharose for PDE binding. Immunoprecipitation with CaBP-D28k antiserum completely inhibited calbindin-mediated activation of PDE but had no effect on calmodulin's ability to activate PDE. While the physiological significance of these results remains to be established, they do suggest that CaBP-D28k can activate enzymes and may be a regulator of yet to be identified target enzymes in certain tissues.
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PMID:In vitro enzyme activation with calbindin-D28k, the vitamin D-dependent 28 kDa calcium binding protein. 131 45

A novel molecule from the arylalkylamine family of drugs, KHL-8430, has been identified as a potent and specific inhibitor of calmodulin activity. The effect of this drug on calmodulin-mediated enzymatic actions has been analyzed to exemplify how to model the mechanism of action of a functional calmodulin antagonist. The approach used includes both binding and enzyme kinetic studies. In both types of experiments, the effects of drugs on calmodulin-phosphofructokinase [ATP:D[fructose-6-phosphate-1-phosphotransferase, EC 2.7.1.11] and calmodulin-phosphodiesterase (3':5' cyclic nucleotide phosphodiesterase, EC 3.6.1.3) interactions have been investigated. We have found that KHL-8430, in contrast to trifluoperazine, a classical anticalmodulin drug, competes with neither phosphofructokinase nor phosphodiesterase for calmodulin binding, yet it liberates phosphofructokinase from calmodulin inhibition and phosphodiesterase from calmodulin stimulation. The anticalmodulin activity occurs at lower KHL-8430 than trifluoperazine concentrations. These findings might establish the functional importance of these differences in the specificity of these drugs. The synthesis of the data suggests that (i) whereas trifluoperazine antagonizes both phosphofructokinase and phosphodiesterase binding to calmodulin, KHL-8430 interacts with calmodulin complexed with enzymes; (ii) KHL-8430 binds to the calmodulin-phosphofructokinase complex with an affinity constant of 0.8 microM, whereas the binding constant of trifluoperazine is 2.5 microM (iii) within the ternary complex the dimeric form of the kinase preserves activity that is otherwise inactive; and (iv) the binding of trifluoperazine and KHL-8430 to calmodulin exhibits negative cooperativity. The approach used in this study makes it possible to screen for the calmodulin antagonist effect of other drugs as well.
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PMID:Dissimilar mechanisms of action of anticalmodulin drugs: quantitative analysis. 214 57

Ca2(+)-ATPase activity in human red cell membranes is dependent on the presence of calmodulin. All trans-retinoic acid inhibited human red cell membrane Ca2(+)-ATPase activity in vitro in a concentration-dependent manner (10(-8) to 10(-4) M). In contrast, retinol, retinal, 13-cis-retinoic acid and the benzene ring analogue of retinoic acid did not alter enzyme activity. Purified calmodulin (up to 500 ng/ml, 3 X 10(-8) M) added to red cell membranes, in the presence of inhibitory concentrations of retinoic acid, only partially restored Ca2(+)-ATPase activity. 125I-Calmodulin bound to red cell membranes was displaced by unlabeled retinoic acid (50% reduction at 10(-8) M retinoic acid), as effectively as by unlabeled calmodulin. Another calmodulin-stimulable enzyme, bovine brain cyclic nucleotide phosphodiesterase, was unaffected by retinoic acid. 8-Anilino-1-naphthalene sulfonic acid bound to calmodulin, studied spectrofluorometrically, was not displaced by retinoic acid. Thus, retinoic acid inhibits calmodulin binding to red cell membranes, reducing calmodulin-stimulable Ca2(+)-ATPase activity. Retinoic acid does not directly interact with calmodulin, but rather exerts its effect by interfering with calmodulin access to the membrane enzyme. These effects occur at physiological concentrations of the retinoid.
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PMID:Retinoic acid inhibits calmodulin binding to human erythrocyte membranes and reduces membrane Ca2(+)-adenosine triphosphatase activity. 216 34


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