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)

Ultrastructural cytochemical localization of ouabain-sensitive, potassium dependent p-nitrophenyl phosphatase (K(+)-NPPase) of the Na(+)-/K(+)-ATPase complex and adenylate cyclase (cAMPase) activities, in washed inactivated human platelets, are described. The one-step lead-citrate method, under similar incubation conditions, was used to determine both activities. K(+)-NPPase appeared in both plasma membrane and the surface-connected canalicular system (SCCS) of the platelets. These data suggest a uniform distribution of the enzyme throughout membrane systems which are in contact with the external medium. cAMPase activity was strictly localized in tubules of the dense tubular system (DTS) when incubation medium contained prostaglandin E1, prostaglandin D2 or forskolin, at concentrations known to stimulate the enzyme in platelets that are intact. This fact and the inhibition of cytochemical reaction by thrombin confirm that the one-step lead-citrate method is a useful procedure in determining adenylate cyclase, abolishing the unfavorable conditions of previously reported methods.
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PMID:Cytochemical localization of K(+)-dependent p-nitrophenyl phosphatase and adenylate cyclase by using one-step method in human washed platelets. 133 Sep 94

To investigate the functional stages of osteoclasts, the ultrastructural histochemical distribution of the lysosomal enzymes [acid phosphatase (tartrate-sensitive) and neutral phosphatase], the plasma membrane enzymes [alkaline phosphatase, Ca(++)-ATPase, and alkaline ouabain-insensitive p-nitrophenylphosphatase (alkaline p-NPPase)], and the mitochondrial enzyme (cytochrome C oxidase) was evaluated in the chicken tibial metaphysis. Both active-appearing and detached (resting) osteoclasts were studied. Serial sectioning was used to identify detached osteoclasts which were present in the perivascular space. The ultrastructure of detached osteoclasts was similar to that of active osteoclasts, except for the lack of a ruffled border and clear zone, and an altered distribution pattern of small vesicles. Small vesicles were uniformly distributed in the cytoplasm of resting osteoclasts, whereas they were concentrated beneath the ruffled border of active osteoclasts. Alkaline p-NPPase, a marker enzyme for the basal ruffled border, was also apparent on the membrane of small vesicles. However, the vesicles did not possess Ca(++)-ATPase, a marker enzyme for the apical plasma membrane. These findings support the concept that small vesicles serve as a membrane reservoir for the ruffled border membrane. Pre-osteoclasts contained abundant mitochondria and lysosomes, prominent Golgi complexes, moderately developed endoplasmic reticulum, and lacked small vesicles. Pre-osteoclasts appear to fuse with osteoclasts which are attached to the bone surface, but not with detached osteoclasts. The small vesicles, from which the ruffled border arises, are absent from pre-osteoclasts, suggesting that they develop after fusion with pre-existing osteoclasts or after attachment to the bone surface. Alkaline p-NPPase appears to be a marker for differentiation of pre-osteoclasts to mature osteoclasts.
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PMID:Characterization of the functional stages of osteoclasts by enzyme histochemistry and electron microscopy. 166 72

9-(2-Phosphonylmethoxyethyl)adenine (PMEA) is a potent and selective inhibitor of retrovirus (i.e., human immunodeficiency virus) replication in vitro and in vivo. Uptake of PMEA by human MT-4 cells and subsequent conversion to the mono- and diphosphorylated metabolites (PMEAp and PMEApp) are dose-dependent and occur proportionally with the initial extracellular PMEA concentrations. Adenylate kinase is unable to phosphorylate PMEA. However, 5-phosphoribosyl-1-pyrophosphate synthetase directly converts PMEA to PMEApp with a Km of 1.47 mM and a Vmax that is 150-fold lower than the Vmax for AMP. ATPase, 5'-phosphodiesterase, and nucleoside diphosphate kinase are able to dephosphorylate PMEApp to PMEAp, albeit to a much lower extent than the dephosphorylation of ATP. PMEApp has a relatively long intracellular half-life (16-18 hr) and has a much higher affinity for the human immunodeficiency virus-specified reverse transcriptase than for the cellular DNA polymerase alpha (Ki/Km: 0.01 and 0.60, respectively). PMEApp is at least as potent an inhibitor of human immunodeficiency virus reverse transcriptase as 2',3'-dideoxyadenosine 5'-triphosphate. Being an alternative substrate to dATP, PMEApp acts as a potent DNA chain terminator, and this may explain its anti-retrovirus activity.
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PMID:Intracellular metabolism and mechanism of anti-retrovirus action of 9-(2-phosphonylmethoxyethyl)adenine, a potent anti-human immunodeficiency virus compound. 170 39

This ultracytochemical study was undertaken to determine whether increased arteriolar permeability in acute hypertension is accompanied by altered localisation of the ouabain-sensitive, K(+)-dependent p-nitrophenyl-phosphatase (K(+)-NPPase), a component of the Na+, K(+)-ATPase system. Rats were injected with horseradish peroxidase (HRP) intravenously and acute hypertension was induced by a 2-min infusion of angiotensin amide. Rats were killed at 3 and 15 min, following which brains were sliced and reacted for demonstration of K(+)-NPPase and HRP reaction product. Vessels of normotensive and hypertensive rats that were nonpermeable to HRP showed discontinuous distribution of K(+)-NPPase on the outer plasma membranes of endothelial and adventitial cells of arterioles and endothelial cells and pericytes of capillaries. Arterioles of the hypertensive rats which were permeable to HRP showed marked reduction of K(+)-NPPase localisation in their walls at 3 min while at 15 min when the blood pressure had returned to resting levels the enzyme localisation was similar to controls. This study demonstrates transient alteration of the NA+, K(+)-ATPase system during increased endothelial permeability in acute hypertension. The implication of this finding and our previous observation of reduced Ca2(+)-ATPase localisation in endothelial plasma membranes in acute hypertension has been discussed.
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PMID:Ultracytochemical localisation of Na+, K(+)-ATPase in cerebral endothelium in acute hypertension. 216 85

We studied the morphological changes and the precise localization of Na+, K(+)-ATPase activity in the developing chick tegmentum vasculosum (TV) with a cytochemical method utilizing K(+)-p-nitrophenylphosphatase (K(+)-NPPase). At stage 37, epithelial folds (lamellae) were relatively well developed, and the light and the dark cells were clearly identified. At stage 41 to 42, Na+, K(+)-ATPase activity appeared in the folded cytoplasmic processes of the dark cells which interdigitated with those of the light cells. The present results indicate that the TV is involved in the production of the cochlear endolymph prenatally (at least up to stage 41), and that the dark cell plays a central role in the maintenance of the ionic composition of the endolymph.
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PMID:Ultracytochemical localization of Na+, K(+)-ATPase activity in the tegmentum vasculosum of the developing chick cochlea. 217 3

Our recent investigations have shown that the Eisai compound, E-0722, (2R-4S-6-fluoro-1-2-methylspirochroman 4,4'-imidazolidine 2,5'-dione) is a more potent aldose reductase inhibitor than Sorbinil (D-6-fluorospirochroman 4,4'-imidazolidine 2,5'-dione). In the previous studies these aldose reductase inhibitors were added to the 50% galactose diet fed to rats to determine their effect on galactose-induced alterations in the lens and the development of cataract. In this report we present our results on the effect of prefeeding the aldose reductase inhibitor, E-0722, on the alterations in rat lens following subsequent feeding of galactose. For this study, young Sprague Dawley rats were prefed either rat chow or rat chow plus 50% galactose containing 1mg/day/Kg body weight of E-0722 for 1 or 2 weeks. After this dietary regimen, the animals were transferred to diets containing 50% galactose for different periods. For controls, rats were fed either rat chow or 50% galactose without the prefeeding of E-0722. Our results obtained through gross observation of the lenses, light microscopic studies of lens sections and assay of Na+-K+-ATPase (NPPase) activity show that the prefeeding of E-0722 prior to galactose feeding delays galactose-induced alterations and the development of mature cataract.
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PMID:Prefeeding of aldose reductase inhibitor and galactose cataractogenesis. 255 45

To study the mode of transepithelial Na+ transport into pancreatic ducts during secretin-dependent NaHCO3 secretion, Na, K-ATPase was first localized within the exocrine pancreas of the pig using a cytochemical reaction for K-dependent p-nitrophenylphosphatase (K-NPPase). K-NPPase staining was confined to the lateral cell membrane bordering the intercellular spaces between ductal cells, negating the possibility of primary active, transcellular Na+ transport into pancreatic ducts. To assess how transepithelial Na+ transport may be coupled to HCO-3 secretion, net flux of Li+ into pancreatic juice was measured following intravenous systemic Li+ loading of 12 secretin infused, anaesthetized pigs. At plasma Li+ 32 (23-35) mmol l-1, Li+ displaced Na+ as accompanying cation to secreted HCO-3, and Li+/Na+ in pancreatic juice matched Li+/Na+ in arterial plasma. During superimposed inhibition of pancreatic water flux by hyperglycaemia, Li+ and Na+ were both transported against a transepithelial concentration gradient. Li+ reduced pancreatic HCO-3 secretion rate by 14 (-2 to -20)%, as well as Na,K-ATPase activity in a separate in vitro assay. The finding that Li+ substituted for Na+ in the secretion even during reduced osmotic water flow suggests that Na+ and Li+ are transported together with secreted HCO-3 into pancreatic juice by an electrogenic mechanism in addition to solvent drag and diffusion.
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PMID:Localization of K-NPPase and Li+ secretion in the exocrine pancreas of the pig. 282 Jan 95

We investigated the distribution of Na+,K+-ATPase in rat exocrine pancreas. By use of enzymatic dissociation techniques, pancreatic acini (containing acinar cells and centroacinar ductal cells in a ratio of about 10:1) and all major classes of pancreatic ducts were isolated and analyzed for the presence of Na+,K+-ATPase using K+-NPPase cytochemistry and [3H]-ouabain binding assays. Ultrastructural analysis demonstrated a basolateral localization of ouabain-sensitive enzyme activity in all classes of pancreatic ducts, although the degree of activity varied among the various classes. Qualitative analysis (scale of 0 to + + +) indicated the following enzyme distribution: centroacinar ductal cells (+); intralobular ducts (+ +); interlobular ducts (+ + +); main duct (+ +). In contrast, no reaction product was associated with pancreatic acinar cells even when observed adjacent to enzyme-positive centroacinar ductal cells. Parallel experiments monitoring [3H]-ouabain binding supported the cytochemical studies. When expressed as femtomoles [3H]-ouabain/microgram DNA, the following values were obtained: whole pancreas, 100.3; ducts (pooled intralobular and interlobular), 337.0; acini, 48.2. The acinar value is complicated by the fact that acini contain both acinar and centroacinar cells, but in light of the cytochemical observations we suggest that most of the [3H]-ouabain binding is due to the few ductal cells present in acini. The results suggest that Na+,K+-ATPase is primarily associated with the ductal epithelium of the exocrine pancreas and is differentially distributed among the different classes of ducts.
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PMID:Distribution of Na+,K+-ATPase in rat exocrine pancreas as monitored by K+-NPPase cytochemistry and [3H]-ouabain binding: a plasma membrane protein found primarily to be ductal cell associated. 282

Vertebrate oxyntic cells, responsible for gastric HCl production, undergo a remarkable morphological reorganization in relation to their secretory cycle. In resting state, the luminal surface of the cells is smooth; a peculiar system of endocellular membranes, the tubular system, occupies the luminal cytoplasm. Actin filaments frame a cortical network between the tubular system and the luminal plasma membrane. With the onset of HCl secretion, the tubular system becomes incorporated into the luminal plasma membrane. Villous processes containing microfilaments fill the secretory surface. This morphological reorganization of membranes and cytoskeletal matrix could regulate HCl secretion by translocation of membranes containing the proton pump from the endocellular compartment to the secretory surface. In this paper, we describe the isolation of membranes that selectively belong to the tubular system or to the cytoplasmic processes of the secretory surface of chicken oxyntic cells. Chicken oxyntic cells are the main cellular component of the proventricular glands. A resting state was obtained after cimetidine treatment, whereas the HCl-secretory state was induced by histamine. We present a comparative analysis of resting and stimulated chicken gastric glands by quantitative subcellular fractionation. The HCl secretory state was related to specific modifications in membrane fractions derived from the secretory pole of oxyntic cells. Morphological and functional reorganization of oxyntic cells was closely correlated with changes in: the sedimentation pattern of the marker enzyme of the apical pole membrane (K-NPPase), the total activity of K-NPPase and nonmitochondrial Mg-ATPase, the valinomycin dependence of K-ATPase, and polypeptides that cosediment in purified membrane fractions. Changes in the distribution pattern of K-NPPase after fractionation of histamine-stimulated glands were consistent with the replacement of the small vesicles typical of resting glands by dense membrane profiles, analogous to the luminal processes of stimulated oxyntic cells. SDS-PAGE showed that, in purified membrane fractions of stimulated glands, the concentration of 28-, 43-, and 200-kD polypeptides increased while that of 95- and 250-kD polypeptides decreased. The present results define the tubular system of oxyntic cells as an organelle with properties different from those of endoplasmic reticulum, mitochondria, and plasma membrane. The biochemical and physico-chemical properties of this membraneous system changed when the organization of the membranes and the cytoskeletal matrix of the apical pole was modified by the onset of HCl secretion.
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PMID:Quantitative subcellular study of apical pole membranes from chicken oxyntic cells in resting and HCl secretory state. 282 94

The effects of starvation, feeding, and time of day on mouse gastric glands were studied by means of an enzyme histochemical method for K+-dependent p-nitrophenyl phosphatase (K+-NPPase), a partial reaction of the proton pump ATPase which drives gastric acid secretion. The stomachs of mice starved for 24 h showed very low levels of parietal cell K+-NPPase histochemical reaction. However, a brief meal following such a period of starvation produced an abrupt increase in K+-NPPase reaction within most of the parietal cell-containing glands though not all parietal cells were equally susceptible to stimulation. The number of glands containing K+-NPPase-reactive parietal cells fell slowly in the hours following a feeding stimulus. These changes were shown to be caused by feeding rather than by general arousal and to follow the feeding cycle in ad libitum fed animals. The reasons that parietal cells in the basal parts of mouse gastric glands cannot be induced to show K+-NPPase reactivity by a feeding stimulus are not understood.
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PMID:Effects of starvation, feeding, and time of day on the activity of proton transport adenosine triphosphatase in the parietal cells of the mouse gastric glands. 284 92


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