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)

Canine renal Na,K-ATPase was treated with ATP dialdehyde, "oxATP" (20 microM), as described by G. Ponzio, B. Rossi, and M. Lazdunski (1983, J. Biol. Chem. 258, 8201-8205). In this system, a by-product, formaldehyde, was the inactivator. We modified the system to minimize such inhibition and to speed up the reaction. oxATP itself inactivated the enzyme at a rate that was slow at first and later speeded up. We fitted a precursor-product model to the data. Labeling with [3H]oxATP indicated about three sites per alpha beta protomer at complete inactivation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the labeled enzyme showed radioactivity in many components, in the alpha and beta subunits and in small molecules at the tracker dye region. ATP (20 mM) prevented all labeling and inactivation. Ponzio et al. concluded that oxATP labels covalently an ATP binding site. Our experiments did not support this conclusion. Ouabain did not affect labeling. Sodium stimulated both inhibition and labeling more than potassium did, indicating a high-affinity ATP binding site, if any. But nucleotide specificity for preventing or producing inhibition did not correspond to nucleotide specificity for binding of ATP to the native enzyme. Blocking the ATP binding center with fluorescein isothiocyanate or fluorosulfonyl benzoyl adenosine had no effect on [3H]oxATP labeling. ATP also prevented [3H]oxATP labeling of bovine serum albumin or of integral-membrane proteins.
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PMID:Inhibition and labeling of sodium, potassium ATPase by the dialdehyde derivative of ATP. 253 59

The effects of cisplatin (5 mg/kg BW given intraperitoneally) on renal concentration mechanism were evaluated initially by clearance studies in rats 5-7 days after cisplatin administration and compared to normal rats. During hypotonic saline infusion, cisplatin rats showed a lower inulin clearance (0.56 +/- 0.07 vs. 1.12 +/- 0.09 ml/min/100 g BW, p less than 0.01), a higher fractional distal delivery (CNa + CH2O/Cin) (36.3 +/- 4.4 vs. 22.8 +/- 4.5%, p less than 0.05), and lower CH2O/CNa + CH2O (33.6 +/- 5.8 vs. 56.5 +/- 5.0%, p less than 0.01). During hypertonic saline infusion the TcH2O/Cosm was lower in cisplatin (18.3 +/- 1.1%) than in normal rats (33.4 +/- 3.5%, p less than 0.01). These results suggest a defect in NaCl transport in the thick ascending limb of Henle and proximal tubule. In order to characterize these tubular defects, we measured Na-K-ATPase activity (microM Pi/mg protein/h). In the renal cortex of cisplatin rats the ATPase activity was lower (18.1 +/- 3.2) than in normal rats (33.4 +/- 6.4, p less than 0.05), also in the inner strip of the outer medulla of cisplatin rats Na-K-ATPase was reduced (26.0 +/- 5.7) when compared with normal rats (67.3 +/- 9.2, p less than 0.01), presumably representing a decrease in enzyme activity in the thick ascending limb.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Renal concentration defect induced by cisplatin. The role of thick ascending limb and papillary collecting duct. 254 10

The effects of aliphatic hydrocarbons within the liposomes on the Ca2+ transport function of isolated sarcoplasmic reticulum (SR) membranes of rabbit skeletal muscle, vesiculate preparation of Ca2+ dependent ATPase and proteoliposomes reconstituted from Ca2+-ATPase and egg phosphatidylcholine, were studied. It was shown that liposomes prepared from dipalmitoyl phosphatidylcholine containing aliphatic hydrocarbons increase 2 to 3 times Ca2+ accumulation by Ca2+-dependent ATPase from rabbit skeletal muscle SR. Ca2+ transport by SR vesicles increases in the presence of hydrocarbons by 15--20%. The activating effect of hydrocarbons on Ca2+ transport by proteoliposomes depends on the lipid/protein ratio. The proteoliposomes with a high lipid/protein ratio are practically insensitive to the effects of hydrocarbons. It was suggested that activation of Ca2+ transport by hydrocarbons is due to blocking of Ca2+ leakage channels formed during the aggregation of Ca2+-ATPase molecules. Treatment of membranes by formaldehyde results in the oligomerization of Ca2+-ATPase and decreases 2--4-fold the ATP-dependent accumulation of Ca2+. Subsequent addition of decane restores Ca2+ transport practically completely.
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PMID:[The blocking effect of aliphatic hydrocarbons on Ca2+ leakage channels formed by aggregates of Ca2+-ATPase of the sarcoplasmic reticulum]. 255 87

To define the role of calmodulin in Ca2+ fluxes behavior of canine masseter muscle sarcoplasmic reticulum (SR) vesicles, the effect of condensation product of N-methyl-p-methoxy-phenethylamine with formaldehyde (compound 48/80), a selective and powerful inhibitor of calmodulin-regulated function, on Ca(2+)-ATPase activity, oxalate-supported Ca2+ uptake velocity, and on interaction with Ca2+ permeability and Ca2+ loading at steady-state were evaluated. Compound 48/80, at concentrations of 10 to 100 micrograms/ml, reduced oxalate-supported Ca2+ uptake velocity without affecting Ca(2+)-ATPase activity. In the presence of 10 micrograms/ml compound 48/80, there was a shift of pH- or temperature-response curve of oxalate-supported Ca2+ uptake velocity, but not of Ca(2+)-ATPase activity, down. It was found that Arrhenius plots of the Ca(2+)-ATPase activity show a break at about 21 degrees C in the presence or absence of 10 micrograms/ml compound 48/80, and that compound 48/80 has no effect on Arrhenius plots of the oxalate-supported Ca2+ uptake velocity. Furthermore, Ca2+ loading at steady-state, but not passive Ca2+ permeability, was decreased by compound 48/80 at low concentrations (1-2 micrograms/ml). The results of this study suggest that calmodulin-dependent process plays a functional role in the coupling of ATP hydrolysis and Ca2+ accumulation, perhaps through regulation of Ca2+ release channels in masseter muscle SR membrane. Calmodulin-dependent component of Ca2+ fluxes in the SR vesicles may be directly modified by compound 48/80, thereby diminishing Ca2+ accumulation without affecting the Ca2+ uptake mechanism.
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PMID:[Effect of compound 48/80 on masseter muscle sarcoplasmic reticulum calcium transport system]. 256 76

The enamel organ of growing rat incisors was perfusion-fixed with a mixture of formaldehyde and glutaraldehyde and processed for ultracytochemical demonstration of ouabain-resistant, K+-stimulated p-nitrophenylphosphatase representing the second dephosphorylative step of H-K-ATPase by use of the one-step lead method. Throughout the stages of amelogenesis, the enzymatic activity was found in the plasma membranes, mitochondrial membranes, and lysosomal structures of the cells of stratum intermedium, papillary layer, and ameloblast layer. Gap junctions and desmosomes between these cells were, however, free of reaction product or showed slight precipitates of reaction. The stellate reticulum and the outer enamel epithelium at the stage of enamel secretion were usually negative for reaction. Although secretory, transition, and ruffle-ended maturation ameloblasts showed enzymatic activity at their basolateral cell surfaces, their distal cell surfaces facing the enamel were always free of reaction product. On the other hand, the smooth-ended maturation ameloblasts seldom showed a positive reaction, except in lysosomes and along their basal cell surfaces. An energy-dispersive X-ray microanalysis of reaction products of H-K-ATPase in unosmicated tissue sections demonstrated that they were composed of lead and phosphorus, which had been released during the dephosphorylation of substrate. In cytochemical controls, the enzymatic activity was completely dependent on substrate and potassium ion, resistant to ouabain and levamisole, and inhibited by nolinium bromide, a specific inhibitor of H-K-ATPase. In addition, inorganic trimetaphosphatase as enzymatic marker of lysosome was localized in dark and pale lysosomes, phagosomes, multivesicular bodies, and ferritin-containing vesicles of the ameloblasts and the cells of stratum intermedium and papillary layer. These membrane-bound structures were also positive for H-K-ATPase reaction. These results suggest that: 1) H-K-ATPase functions to maintain an acidic internal pH of lysosomes in the enamel organ cells; and 2) H-K-ATPase localization in the plasma membranes of enamel organ cells is concerned with efflux of protons derived from cytoplasmic water.
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PMID:H+-K+-ATPase activity in the rat incisor enamel organ during enamel formation. 284 91

Methanogenesis from formaldehyde or formaldehyde + H2, as carried out by Methanosarcina barkeri, was strictly dependent on sodium ions whereas methane formation from methanol + H2 or methanol + formaldehyde was Na+-independent. This indicates that the reduction of formaldehyde to the formal redox level of methanol exhibits a Na+ requirement. During methanogenesis from formaldehyde, a delta pNa in the range of -62 mV to -80 mV was generated by means of a primary, electron-transport-driven sodium pump. This could be concluded from the following results obtained on cell suspensions of M. barkeri. 1. The addition of proton conductors or inhibitors of the Na+/H+ antiporter had no effect on sodium extrusion. 2. During methanogenesis from formaldehyde + H2 a delta psi of -60 mV to -70 mV was generated even in the presence of proton conductors. 3. ATPase inhibitors, applied in the presence of proton conductors, had no effect on primary sodium extrusion or generation of a delta psi. Evidence for a Na+-translocating ATPase could not be obtained.
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PMID:Electron-transport-driven sodium extrusion during methanogenesis from formaldehyde and molecular hydrogen by Methanosarcina barkeri. 285 Jan 82

Immunohistochemical techniques have been used to localize clotting factor XIII subunit A in human reactive lymphoid follicles. The follicular dendritic reticulum cells (DRCs) were identified by the monoclonal antibodies R4/23 and OKB-7 as well as by their 5'-nucleotidase positivity. Follicular histiocytic reticulum cells (HRCs) were demonstrated by their acid phosphatase and non-specific esterase reactions. Capillaries were selectively visualized by adenosine triphosphatase. The immunohistochemical demonstration of F-XIIIa was preferably carried out in combination with one or two of the above marker techniques, on the same cryostat section. The subunit A of factor XIII is present in follicular DRCs. Their selective immunohistochemical demonstration with antibody against F-XIIIa requires formaldehyde fixation of cryostat sections. Similar fixation, however, is inappropriate for the demonstration of F-XIIIa reactivity of DRCs in paraffin sections. For this purpose, acetic acid-formalin fixation is useful. Follicular HRCs are consistently negative for F-XIIIa, contrary to the F-XIIIa positivity of sinusoidal and interfollicular HRCs. Developmental and functional implications of F-XIIIa reactivity in DRCs and HRCs are suggested.
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PMID:Selective visualization of human dendritic reticulum cells in reactive lymphoid follicles by the immunohistochemical demonstration of the subunit A of factor XIII (F-XIIIa). 288 67

The association of an ATPase with the yeast peroxisomal membrane was established by both biochemical and cytochemical procedures. Peroxisomes were purified from protoplast homogenates of the methanol-grown yeast Hansenula polymorpha by differential and sucrose gradient centrifugation. Biochemical analysis revealed that ATPase activity was associated with the peroxisomal peak fractions which were identified on the basis of alcohol oxidase and catalase activity. The properties of this ATPase closely resembled those of the mitochondrial ATPase of this yeast. The enzyme was Mg2+-dependent, had a pH optimum of approximately 8.5 and was sensitive to N,N'-dicyclohexylcarbodiimide (DCCD), oligomycin and azide, but not to vanadate. A major difference was the apparent Km for ATP which was 4-6 mM for the peroxisomal ATPase compared to 0.6-0.9 mM for the mitochondrial enzyme. Cytochemical experiments indicated that the peroxisomal ATPase was associated with the membranes surrounding these organelles. After incubations with CeCl3 and ATP specific reaction products were localized on the peroxisomal membrane, both when unfixed isolated peroxisomes or formaldehyde-fixed protoplasts were used. This staining was strictly ATP-dependent; in controls performed in the absence of substrate, in the presence of glycerol 2-phosphate instead of ATP, or in the presence of DCCD, staining was invariably absent. Similar staining patterns were observed in subcellular fractions and protoplasts of Candida utilis and Trichosporon cutaneum X4, grown in the presence of ethanol/ethylamine or ethylamine, respectively.
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PMID:A proton-translocating adenosine triphosphatase is associated with the peroxisomal membrane of yeasts. 288 51

The enamel organ of the growing rat incisor was fixed with a mixture of formaldehyde and glutaraldehyde and processed for ultracytochemical demonstration of Ca- and Mg-activated membrane ATPase by a one-step lead technique at alkaline pH. To inhibit nonspecific alkaline phosphatase, 5 mM levamisole was added to the incubation media. Intense Ca- and Mg-ATPase activity was demonstrated in the cell surfaces of the secretory ameloblasts, except at the proximal and distal junctional complexes and the gap junctions in the lateral and basal cell surfaces. Deep plasma membrane invaginations at the proximal and distal parts of Tomes processes facing interrod- and rod-enamel growth regions exhibited the strongest enzymatic reaction. Mg-ATPase activity was also shown to be present in the plasma membranes of secretory ameloblasts but it was less intense than Ca-ATPase. Except for a slight reaction in the Golgi membranes, all other cell organelles of the secretory ameloblasts and the adjacent enamel matrix were free of enzymatic reaction. However, when the tissues were incubated in media lacking levamisole, a prominent enzymatic reaction was observed in the newly secreted enamel matrix of the rod and interrod growth regions as well as on the plasma membranes of the cells. In maturation ameloblasts of both ruffle-ended and smooth-ended types, a weak reaction for Ca- and Mg-ATPase was restricted to basal cell surfaces facing the papillary cell layer. In tissues incubated in media lacking levamisole, a variable deposition of reaction products was observed in the Golgi membranes, mitochondrial membranes, tubular elements of smooth endoplasmic reticulum in the ruffled border zone, and along the plasma membranes of the ruffled border. Throughout the secretory and maturation stages, a moderate and/or weak enzymatic reaction for both Ca- and Mg-ATPase was seen in the plasma membranes of the cells of the stratum intermedium and the papillary layer when incubated in media with levamisole. Omission of substrate ATP and/or the enzyme activator CaCl2 from the incubation media for Ca-ATPase produced a negative reaction in the tissues examined. When the calmodulin blocker trifluoperazine was administered to the rats intravenously, Ca-ATPase activity was almost completely abolished from the plasma membranes of secretory ameloblasts, but not of other cell types.
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PMID:Ultracytochemical demonstration of ATP-dependent calcium pump in ameloblasts of rat incisor enamel organ. 294 78

Glutaraldehyde treatment of sarcoplasmic reticulum vesicles results in formation of cross-linked Ca2+-ATPase oligomers. Under limiting reaction conditions, where minimal interpolypeptide cross-linking occurs, hydrodynamic properties of the monomer are altered, such that, on sodium dodecyl sulfate-polyacrylamide electrophoresis, the enzyme migrates with an apparent molecular weight of 125,000 (E(125], as compared to the native enzyme (E(110]. The E(125) species was also formed following reaction with other cross-linking bis-aldehydes, with formaldehyde and with a bissuccinimidyl ester. Derivitization resulted in inactivation of ATPase activity and of phosphoprotein formation from Pi. E(125) formation was inhibited by ATP, ADP, AMPPCP, and orthovanadate, and by specific modification of active site Lys-514 with fluorescein-5'-isothiocyanate. Tryptic cleavage patterns of the glutaraldehyde-modified enzyme were consistent with covalent linkage of A1 and B fragments that have been postulated to comprise the phosphorylation and nucleotide-binding domains (MacLennan, D. H., Brandt, C. J., Korczak, B., and Green, N. M. (1985) Nature 316, 696-700). The denaturing detergent, sodium dodecyl sulfate, prevented cross-link formation. Interdomain cross-linking was inhibited by prior modification with either 2,4,6-trinitrobenzene sulfonate, phenylglyoxal, or pyridoxal-5'-phosphate but was unaffected by thiol group modification with iodoacetate or N-ethylmaleimide, suggesting involvement of lysine residues. These findings indicate that intramolecular cross-linking at the active site of the Ca2+-ATPase involves phosphorylation- and ATP-binding domains that are widely separated in the linear sequence.
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PMID:Intramolecular cross-linking of domains at the active site links A1 and B subfragments of the Ca2+-ATPase of sarcoplasmic reticulum. 295 84


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