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)

1. The origin of the limiting membranes of autophagic vacuoles (AVs) in mouse pancreatic acinar cells was studied in vinblastine-induced autophagocytosis. 2. The marker enzymes used were adenosine triphosphatase, lipase, inosine diphosphatase and thiamine pyrophosphatase. The following impregnation techniques were used: unbuffered osmium tetroxide impregnation, imidazole-buffered osmium tetroxide impregnation and uranyl-lead-copper impregnation. 3. Only a weak lipase activity was observed between the limiting membranes of a few AVs. The AV membranes were stained heavily with all impregnation techniques used. 4. The origin of AV membranes seems to be same in mouse liver and exocrine pancreas in vinblastine-induced autophagocytosis.
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PMID:Cytochemical studies on induced autophagocytosis in mouse exocrine pancreas. 245 89

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on Ca2+-adenosine triphosphatase (ATPase) activity in hepatic microsomes was investigated. Mg2+-ATPase activity was clearly increased by the presence of 50 microM Ca2+. Regucalcin (1.0-4.0 microM) caused a remarkable elevation (about 3-fold) of Ca2+-ATPase activity. Also, Mg2+-ATPase activity was increased (about 1.6-fold) by the presence of regucalcin (2.0 and 4.0 microM). Guanosine-5'-O-(3-thiotriphosphate) (GTPrs; 10(-5) and 10(-4) M) and nicotinamide adenine dinucleotide phosphate oxidized form (NADP+; 10(-5) to 10(-3) M) or reduced form (NADPH; 10(-4) and 10(-3) M) significantly increased Ca2+-ATPase activity. These increases were not enhanced by the presence of regucalcin (2.0 microM). Of various metal ions, a comparatively low concentration of V5+ (10(-5) M) or Cd2+ (10(-6) M) significantly increased Ca2+-ATPase activity, while Hg2+, Zn2+, Cu2+ and Mn2+ did not have such an effect. Regucalcin (2.0 microM) did not enhance the effect of V5+ and Cd2+ on Ca2+-ATPase activity. The present finding, that regucalcin activates hepatic microsomal Ca2+-ATPase, suggests a cell physiological role of regucalcin as an activator in the microsomal Ca2+-pump activity. This action of regucalcin may not be influenced by other regulators.
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PMID:Activation of hepatic microsomal Ca2+-adenosine triphosphatase by calcium-binding protein regucalcin. 252 22

1. Reidentifiable Aplysia neurones were current and voltage clamped in vitro using standard microelectrode techniques. 2. Bath or focal application of Cu2+ at concentrations of 1-100 microM produced a rapid and reversible depolarization of the somal, but not the axonal, membrane potential. The depolarization was accompanied by an increased membrane conductance and activation of an inward current (ICu) which could not be activated by intracellular ionophoretic injection of Cu2+. 3. ICu is carried, in part, by Na+ because the reversal potential of ICu was shifted in a Nernstian fashion by decreasing the extracellular Na+ concentration. The reversal potential of ICu was not affected by removal of extracellular Ca2+ or K+. 4. ICu does not result from (1) activation of known chemically or voltage-gated Na+ conductances, (2) inhibition of the Na+-K+-ATPase or (3) a generalized increase in membrane permeability resulting from lipid peroxidation. 5. A similar inward current was activated by AgNO3 (100 microM) and HgCl2 (100 microM).
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PMID:Copper activates a unique inward current in molluscan neurones. 283 93

Adenine nucleotide translocase in electron transport particles or in H+-ATPase preparation from bovine heart mitochondria is capable of forming both inter- and intramolecular disulfide bridges upon reaction with copper-o-phenanthroline. We have examined the localisation of the intramolecular disulfide bridge in the protein chain by peptide fragmentation methods. The most likely position of the disulfide bridge is between cysteine 159 and 256, but the possibility of the presence of a second disulfide bridge formed between 129 and 256 cannot be ruled out. Our experimental results support the theoretical model proposed [(1982) FEBS Lett. 144, 250-254] for the topography of the translocase and provide a more accurate description of the arrangement of some of the hydrophilic segments in the molecule.
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PMID:Formation of an intramolecular disulfide bond in the mitochondrial adenine nucleotide translocase. 285 6

The nearest neighbor relationships between the Fo subunits of bovine mitochondrial H+-ATPase were studied by using copper-o-phenanthroline, an SH-oxidizing cross-linking reagent. The cross-linked samples of purified H+-ATPase, F1-ATPase or Fo were analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) and the disulfide cross-linked polypeptides were identified by enzyme-linked immunosorbent assay and immunoblot transfer using subunit specific antisera. SDS-PAGE of H+-ATPase showed several cross-links, although none involved subunits of Fo sector linked to those of F1. Both H+-ATPase and Fo showed formation of a 45-kDa product. Upon reduction, the 45-kDa component gave rise to a 21-kDa band, identified as oligomycin-sensitivity-conferring protein (OSCP), and a 24-kDa band. These two proteins thus appear to be near neighbors with their cysteine residues in close proximity with each other. Under the conditions of cross-linking, there was a concentration-dependent decrease in the Pi-ATP exchange activity of the intact H+-ATPase as well as of H+-ATPase reconstituted with copper-o-phenanthroline-treated Fo and untreated F1. The site of inhibition appeared to residue in the Fo sector. Loss of Pi-ATP exchange occurred at the same time as formation of the 45-kDa product. Our present data showing copper-o-phenanthroline-induced interactions of the 24-kDa protein with the OSCP and simultaneous inactivation of Pi-ATP exchange activity of the complex strengthen earlier suggestions [Hadikusumo, R.G., Hertzog, P.J. & Marzuki, S. (1984) Biochim. Biophys. Acta 765,258-267] that the 24-kDa protein may be a bona fide subunit of Fo.
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PMID:Cross-linking of bovine mitochondrial H+-ATPase by copper--o-phenanthroline. Interaction of the oligomycin-sensitivity-conferring protein with a 24-kDa protein. 286 96

The divalent cation (o-phenanthroline)2-Cu2+ complex was found to uncouple oxidative phosphorylation in mitochondria. Its uncoupling activity depended on inorganic phosphate (Pi) in the incubation medium, and was inhibited by the SH-reagent N-ethylmaleimide, and retarded by ATP. The uncoupling by the (o-phenanthroline)2-Cu2+ complex was suggested to be due to its modification of sulfhydryl groups in the 29 kDa protein in H+-ATPase.
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PMID:Possible involvement of the 29 kDa protein in H+-ATPase in the action of cationic uncoupler of oxidative phosphorylation. Effect of the (o-phenanthroline)2-Cu2+ complex as a cationic uncoupler. 288 Jun 5

The Mr 170,000 to 180,000 membrane glycoprotein associated with multidrug resistance (P-glycoprotein) is involved in drug transport mechanisms across the plasma membrane of multidrug-resistant cells. We have recently reported the purification of P-glycoprotein. The purified P-glycoprotein was found to have an ATPase activity, which might be coupled with the active efflux of anticancer drugs. In the present study, we have further studied the properties of the P-glycoprotein ATPase activity by an immobilized enzyme assay procedure using a P-glycoprotein-antibody-Protein A-Sepharose complex. GTP was also hydrolyzed by the P-glycoprotein, although less efficiently than ATP. The ATPase activity of P-glycoprotein had an optimal pH range around neutrality (pH 6.5-7.4). The detergent concentration of 3-[(3-cholamidopropyl)dimethyl-ammonio]-1-propane sulfonate used for protein solubilization was essential for enzyme recovery. Maximum activity was obtained when 0.1-0.2% 3-[(3-cholamidopropyl)dimethyl-ammonio]-propane sulfonate was used, while higher concentrations markedly inhibited the ATPase activity. The ATPase activity was dependent on Mg2+; maximum activity was obtained at 2-10 mM. Manganese and cobalt could substitute for magnesium as ionic cofactors. Divalent cations such as Ca2+, Zn2+, Ni2+, Cd2+, and Cu2+ inhibited the Mg2+-catalyzed ATP hydrolysis. N-Ethylmaleimide and vanadate inhibited the ATPase activity, while sodium azide or ouabain had no effect. Anticancer agents such as vincristine and Adriamycin did not affect the enzyme activity. In contrast, verapamil and trifluoperazine, agents which inhibit active drug efflux and restore drug sensitivity in resistant cells, caused an increase in the P-glycoprotein ATPase activity suggesting that P-glycoprotein might be the target molecule of these agents.
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PMID:Characterization of the ATPase activity of the Mr 170,000 to 180,000 membrane glycoprotein (P-glycoprotein) associated with multidrug resistance in K562/ADM cells. 290 Jun 77

The microsomal Mg-ATPase from various rat tissues was compared. After fractionating the microsomal vesicles by sucrose gradient centrifugation, the highest specific activity of the Mg-ATPase was found in the low-density vesicles which contained plasma membrane. A large fraction (25-90%) of the microsomal Ca-independent Mg-ATPase found in each tissue had the following properties: (1) the Km for ATP was 0.2 mM; (2) the rate of ATP hydrolysis by the Mg-ATPase was nonlinear due to an ATP-stimulated inactivation of the enzyme; (3) wheat germ agglutinin, concanavalin A, glutaraldehyde, and antiserum prevented inactivation induced by ATP or AdoPP[NH]P; (4) detergents at relatively low detergent:protein ratios increased the rate of inactivation with little change in the initial rate of ATP hydrolysis; (5) the Mg-ATPase was inactivated by irradiation in the presence of 8-azido ATP. (6) in addition to ATP, the Mg-ATPase was able to hydrolyze CTP, GTP, UTP, ITP, and GTP but was unable to hydrolyze any of the 10 nonnucleotide phosphocompounds which were tested; (7) the bivalent cation requirement of the Mg-ATPase could be provided by Mg2+, Ca2+, Mn2+, Zn2+, or Co2+ but the enzyme was inactive in the presence of Cu2+, Sr2+, Ba2+, or Be2+; (8) the Mg-ATPase activity was not altered by ionophores or inhibitors of the Na,K-ATPase, the Ca,Mg-ATPase or the mitochondrial F1ATPase. These data suggest that a major portion of the microsomal, basal Mg-ATPase activity is due to one unique enzyme found in most if not all tissues.
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PMID:Comparison of the rat microsomal Mg-ATPase of various tissues. 293 82

The effect of increasing sucrose concentrations on some mitochondrial functions was studied. The results showed that high osmolarity inhibits oxidative phosphorylation as well as ATPase activity and ATP-dependent delta phi formation as a consequence of adenine nucleotide translocase inhibition. It is also shown that high osmolarity does not affect delta phi formation and energy-dependent Ca2+ uptake as driven by succinate oxidation. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of membrane proteins showed a different reactivity to o-phenantroline/Cu2+ as function of osmolarity. It is proposed that high sucrose concentrations induce a collapse of the matrix compartment that results in a restricted diffusion of some metabolites.
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PMID:Metabolite transport in mitochondria as a function of osmolarity. 294 2

Acetylcholinesterase (AchE: EC 3.1.1.7) was identified and purified from the hemolymph of the scorpion Heterometrus bengalensis. The purity of the enzyme was determined by polyacrylamide gel electrophoresis (PAGE). The molecular weight of the enzyme, determined by sodium dodecyl sulfate-PAGE, was 80,000. The purified AchE hydrolysed acetylthiocholine iodide, but it did not react with butyrylthiocholine iodide. BW284C51, a specific inhibitor of AchE, strongly inhibited the enzyme. The known inhibitor (tetramonoisopropylpyrophosphortetramide) of pseudocholinesterase did not produce any inhibition of the enzyme activity. The purified AchE of scorpion hemolymph was vulnerable to high substrate concentration. The presence of Cu2+ and Ni2+ reduced the enzyme activity, whereas the metal ion, Sn2+, enhanced AchE activity. Ca2+ produced neither inhibition nor activation. (Na+, K+)-ATPase and Mg2+-ATPase activities were greatly enhanced by the purified AchE.
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PMID:Acetylcholinesterase (EC 3.1.1.7), a neurotransmitter enzyme in scorpion hemolymph. 296 37


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