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 subcellular localization of the omega-hydroxylase of Saccharomycopsis lipolytica was assessed by the analytical fractionation technique, originally described by de Duve C., Pressman, B.C., Gianetto, R., Wattiaux, R. and Appelmans, F., and hitherto little, if at all, applied to yeasts. Protoplasts were separated in six fractions by differential centrifugation. Some of these fractions were further fractionated by density gradient centrifugation. The distribution of omega-hydroxylase and 15 other constituents chosen as possible markers of its subcellular entities. (1) Mitochondria were characterized by particulate malate dehydrogenase, particulate Antimycin A-insensitive NADH-cytochrome c reductase, oligomycin-sensitive and K+-stimulated ATPase pH 9. (2) Most if not all of the catalase and urate oxidase is peroxisomal. (3) Free ribosomes account for most RNA. (4) Nucleoside diphosphatase is for the first time reported in a yeast and appears to belong to an homogeneous population of small membranes. (5) The soluble compartment contains magnesium pyrophosphatase, alkaline, 5'-nucleotidase and part of the NADH-cytochrome c reductase. Latent arylesterase and ATPase pH 7 have an unspecific distribution. Alkaline phosphodiesterase I has not been detected.
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PMID:Subcellular distribution of enzymes in the yeast saccharomycopsis lipolytica, grown on n-hexadecane, with special reference to the omega-hydroxylase. 626 2

Na+,K+-ATPase was localized at the ultrastructural level in rat and rabbit kidney medulla. The cytochemical method for the K+-dependent phosphatase component of the enzyme, using p-nitrophenylphosphate (NPP) as substrate, was employed to demonstrate the distribution of Na+, K+-ATPase in tissue-chopped sections from kidneys perfusion-fixed with 1% paraformaldehyde-0.25% glutaraldehyde. In other outer medulla of rat kidney, ascending thick limbs (MATL) were sites of intense K+-dependent NPPase (K+-NPPase) activity, whereas descending thick limbs and collecting tubules were barely reactive. Although descending thin limbs (DTL) of short loop nephrons were unstained, DTL from long loop nephrons in outer medulla were sites of moderate K+-NPPase activity. In rat inner medulla, DTL and ascending thin limbs (ATL) were unreactive for K+-NPPase. In rabbit medulla, only MATL were sites of significant K+-NPPase activity. The specificity of the cytochemical localization of Na+,K+-ATPase at reactive sites in rat and rabbit kidney medulla was demonstrated by K+-dependence of reaction product deposition, localization of reaction product (precipitated phosphate hydrolyzed from NPP) to the cytoplasmic side of basolateral plasma membranes, insensitivity of the reaction to inhibitors of nonspecific alkaline phosphatase, and, in the glycoside-sensitive rabbit kidney, substantial inhibition of staining by ouabain. The observed pattern of distribution of the sodium transport enzyme in kidney medulla is particularly relevant to current models for urine concentration. The presence of substantial Na+,K+-ATPase in MATL is consistent with the putative role of this segment as the driving force for the countercurrent multiplication system in the outer medulla. The absence of significant activity in inner medullary ATL and DTL, however, implies that interstitial solute accumulation in this region probably occurs by passive processes. The localization of significant Na+,K+-ATPase in outer medullary DTL of long loop nephrons in the rat suggests that solute addition in this segment may occur in part by an active salt secretory mechanism that could ultimately contribute to the generation of inner medullary interstitial hypertonicity and urine concentration.
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PMID:Ultrastructural localization of Na+,K+-ATPase in rat and rabbit kidney medulla. 627 10

1. The activity of the overall Na+-K+-ATPase reaction was inhibited by indomethacin in vitro. 2. The K+-NPPase activity was also inhibited by indomethacin. 3. The activity of Na+-dependent phosphorylation of Na+-K+-ATPase was activated by indomethacin. 4. Indomethacin required for 50% inhibition of K+-NPPase activity was 0.4 mM. 5. Inhibition mode of indomethacin for both the substrate and K+ in K+-NPPase reaction was competitive type. 6. The Ki values for indomethacin for the substrate and K+ in K+-NPPase reaction were 0.4 and 0.24 mM, respectively. 7. Inhibitory effect of indomethacin on K+-NPPase was reversible.
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PMID:Mode of inhibition of activity of Na+-K+-stimulated adenosine triphosphatase by indomethacin. 629 11

Ultrastructural localization of the phosphatase component of Na-K-ATPase in the inner ear of the guinea pig was studied utilizing p-nitrophenyl phosphate (NPP) as substrate. In the stria vascularis NPPase activity was restricted to the cytoplasmatic side of the basal plasma membranes of the marginal cells. In the spiral prominence enzyme activity was resolved only occasionally on the basolateral membranes of the spiral prominence epithelium, especially after longer incubation periods. The remaining inner ear tissue was unreactive. Possible transport mechanisms of potassium across the apical marginal cell membrane are discussed.
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PMID:Ultrastructural localization of K+-dependent, ouabain-sensitive NPPase (Na-K-ATPase) in the guinea pig inner ear. 630 Dec 5

The ultracytochemical localization of eight hydrolytic enzymes (TMPase, 5'-NPase, TPPase, TTPase, Mg++-ATPase, Ca++-ATPase, ALPase and K+-NPPase) and one oxidative enzyme (MAO) was determined in rat brain capillary endothelial cells. In the somal plasma membrane, the enzymatic activity was mainly located in the antiluminal plasma membrane. This finding was appropriate for enzymes possessing the optimal pH at alkaline ranges, except for alkaline phosphatase. Most enzymes investigated showed a positive reaction on the pinocytotic vesicles of capillary endothelial cells. Differences in the intensity of the enzyme activities of the luminal and antiluminal plasma membranes may reflect the polarity in the capillary endothelial cells and relate to blood-brain barrier mechanisms.
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PMID:Ultracytochemical studies of capillary endothelial cells in the rat central nervous system. 632 56

Ouabain-sensitive, K-dependent p-nitrophenylphosphatase (K- NPPase ) activity of the Na-K-ATPase complex and the Ca-ATPase activity were studied ultracytochemically in the inner and outer segments of guinea pig photoreceptor cells by means of newly developed methods. The K- NPPase activity was demonstrated on the plasmalemma of the inner segments, whereas the Ca-ATPase activity was restricted to the matrix side of the inner membrane of the mitochondria which were accumulated in the inner segments. In contrast to the enzyme activities in the inner segments no such activity could be detected on the plasma and disk membranes of the outer segments. The functional meaning of the enzyme activities is discussed.
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PMID:Localization of ATPases in retinal receptor cells. 632 96

Vanadate in redox state +5 inhibited the Na+K+-activated ATPase as well as the potassium-stimulated p-nitrophenylphosphatase (p-NPPase) activities of plasma membrane fragments prepared from rat brain. Vanadate exhibited a mixed type inhibition on the Na+K+-ATP-ase activity. The same type of inhibition was observed when the p-NPPase activity of the enzyme preparation was measured either in the presence of 20 mM K+ or with 5 mM Na+ + 1 mM K+. When the reaction mixture contained 50 microM ATP, 5 mM Na+ and 1 mM K+, inhibition of p-NPP hydrolised by vanadate displayed a noncompetitive character. Higher noradrenalin concentration was required for counteracting, the inhibition of p-NPPase by vanadate in the presence of ATP than in its absence.
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PMID:Vanadate inhibition of Na+K+. ATPase and K+-dependent p-nitrophenylphosphatase: a kinetic analysis. 633 Oct 47

A procedure for cellular fractionation and preparation of plasma membrane from a Burkitt's lymphoma cell line is described. This procedure involves homogenization with a Polytron in buffered isotonic sucrose, and separation of cellular fractions by differential and isopycnic centrifugation in sucrose. The isolated plasma membrane fraction contains 44% of the cellular cholesterol, 50% of the ouabain-sensitive (Na+ + K+)-ATPase activity, 43% of the gamma-glutamyltranspeptidase activities and 16% of the phospholipid. This fraction contains only 3% of cellular protein and is contaminated with less than 4% of the total cellular activities of microsomal, lysosomal, mitochondrial, Golgi and soluble marker enzymes. The cholesterol : phospholipid molar ratio of the crude plasma membrane is 0.56. The membranes in this fraction are in the form of vesicles. Further purification of plasma membrane is achieved by sucrose density gradient centrifugation and results in a 25- to 30-fold enrichment of plasma membrane markers. Plasma membrane markers band in these gradients between 1.10 and 1.15 g/cm3. The distribution patterns in the cell fractions of 18 cellular constituents are quantitatively determined. Most constituents are found to distribute in a fashion consistent with the results obtained in other systems. Thymidine-5'-phosphodiesterase (phosphodiesterase I), esterase, nucleoside diphophatase and glucose-6-phosphatase, however, are shown to be poor markers of membrane fractions in this system. Lactoperoxidase-catalyzed iodination was used to identify several plasma membrane proteins which are exposed at the surface. After separation of labeled polypeptides by sodium dodecyl sulfate gel electrophoresis, the predominant labeled protein was identified as the heavy chain of IgM. Several lesser labeled proteins were observed.
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PMID:Cellular fractionation and isolation of the plasma membrane of Burkitt's lymphoma cells. 740 42

Recently, we isolated from the urine of salt-loaded healthy subjects a more polar ouabain-like factor OLF-1 and a more apolar OLF-2, the latter cross-reacted with a digoxin anti-body. They were purified to single compounds with dose-dependent Na-K-ATPase inhibition. Mass-spectroscopy (MS) showed a Mr of around 400 and 1H-NMR- and IR-spectroscopy suggested diascorbic acid salts, i.e., vanadium (V) diascorbates (Mr 403) with similar elution times from RP-HPLC as OLFs. IC50 was 9 x 10(-5)M for VIV-diascorbate as compared to 2 x 10(-6)M for Vv-diascorbate. Enzyme inhibition was non-competitive with respect to sodium and Mg-ATP; p-NPPase assay showed strong inhibition in its E2-configuration. We suggest that V-diascorbates represent endogenous OLFs excreted in human urine.
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PMID:Vanadium-diascorbates are strong candidates for endogenous ouabain-like factors in human urine: effects on Na-K-ATPase enzyme kinetics. 763 47

It is believed that the function of the stria vascularis in the cochlea is to produce endolymph. However, the mechanisms that maintain and control the function of the stria vascularis remain unclear. In the present study, to clarify the role of humoral substances in the stria vascularis, a cerium-based method was used to investigate the ultracytochemical effects of intraperitoneal dopamine administration on ouabain-sensitive, K(+)-dependent, p-nitrophenylphosphatase (K-NPPase) activity, which is the second step in the formation of the Na-K ATPase complex, in the stria vascularis of guinea pigs. Na-K ATPase activity was shown to be completely inhibited after dopamine administration. This observation suggests that dopamine inhibits Na-K ATPase activity in the marginal cells of the stria vascularis, and that the stria vascularis may have dopamine receptors. Catecholamines may play an important role in the maintenance and/or control of stria vascularis function.
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PMID:Dopamine inhibits the Na-K ATPase activity of the stria vascularis in the cochlea. In vivo ultracytochemical study. 776 79


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