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)

Ouabain-sensitive, K(+)-dependent, p-nitrophenylphosphatase (K-NPPase) is the second dephosphorylative property of the Na-K ATPase complex. Localization of its activity in the horizontal portion of the facial nerve in 11 normal cats was studied ultracytochemically using a cerium-based method. The fine granular reaction product of the K-NPPase activity was observed on the cytoplasmic side of the axolemma of the axon cylinder. Enzyme activity was also detected on the cytoplasmic side of the plasma membrane of Schmidt-Lanterman incisures and nodes of Ranvier. No reaction product was detected on the periaxonal and outermost plasma membrane of Schwann cells and in the myelin sheath. In control tissue samples, enzyme activity was almost completely inhibited by 10 mM ouabain, and no reaction was noted in medium without K+. The present findings indicate that localization of Na-K ATPase in the cat facial nerve simulates that of other peripheral and cranial nerves.
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PMID:Ultracytochemical demonstration of ouabain-sensitive, K(+)-dependent, p-nitrophenylphosphatase (Na-K ATPase) activity in cat facial nerve. 791 58

A monoclonal IgG, directed to phosphatidylserine (PS1G3), partially (40-50%) inhibited Na+/K(+)-ATPase activity (forward running reaction cycle) without affecting the K0.5 values for Na+,K+ and MgATP. The Hill or interaction coefficients (nH) for Na+ and K+ for this reaction were reduced from 3.0 to 1.6 and from 1.6 to 0.8, respectively. The K(+)-stimulated p-nitrophenylphosphatase activity (p-NPPase), which is a partial reaction sequence of the Na+/K(+)-ATPase system (but in the backward running mode), was inhibited more strongly (about 70%) due to an increase in K+/substrate antagonism. In this system K0.5 and nH values for both p-nitrophenyl phosphate (p-NPP) and K+ were increased by the mAb. At the maximally inhibitory concentration of PS1G3 the Vmax of the p-NPPase was also reduced. Partial reactions, which were inhibited by PS1G3, are: (1) the Na(+)-activated phosphorylation (non-competitive vs. Na+), (2) the Rb+ occlusion (competitive vs. Rb+). Partial reactions not harmed by PS1G3 are: (3) the K(+)-dependent dephosphorylation, (4) the K(+)-dependent E1 + K+<-->E2K transition. We conclude that PtdSer is involved in cation occlusion, possibly by forming part of the access gate.
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PMID:Monoclonal antibody to phosphatidylserine inhibits Na+/K(+)-ATPase activity. 807 30

The Na+,K(+)-ATPase is an important enzyme in determining the ionic milieu of the cerebromicrovasculature and neurons. The effect of hypertension or aging on this enzyme, as well as its susceptibility to regulation by fatty acids or aluminum, is the focus of this study. A significant increase (34%) in the apparent affinity constant (KD) but no change in the maximum binding capacity (Bmax) for [3H]ouabain binding to the cerebromicrovascular Na+,K(+)-ATPase occurs after induction of acute hypertension. In addition, long chain unsaturated fatty acids stimulate the binding of [3H]ouabain to the enzyme in microvessels from normotensive and hypertensive rats. The synaptosomal Na+,K(+)-ATPase is sensitive to aluminum. AlCl3 (1-100 microM) inhibits the K(+)-dependent-p-nitrophenylphosphatase (K(+)-NPPase) activity of the Na+,K(+)-ATPase in a dose-dependent manner. AlCl3 (100 microM) decreases the Vmax by 14% but does not alter the KM, suggestive of non-competitive inhibition. The enzyme from aged brain displays a greater Vmax, but shows the same susceptibility to AlCl3 as the enzyme from younger brain. In summary, disruption of the Na+,K(+)-ATPase may underlie, at least in part, abnormalities of nerve and vascular cell function in disorders where elevated concentrations of fatty acids or metal ions are involved.
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PMID:Control of the Na+,K(+)-ATPase under normal and pathological conditions. 810 35

The localization of ouabain-sensitive, K(+)-dependent p-nitrophenylphosphatase (K-NPPase) activity, the second dephosphorylative property of the Na-K adenosine triphosphatase complex, was cytochemically studied in the intra-temporal portion of the facial nerve in normal guinea pigs using a cerium-based method. A fine-granular reaction product of the K-NPPase activity was observed on the cytoplasmic side of the axolemma of the axon cylinder, of the incisures of Schmidt-Lanterman, and of the nodes of Ranvier. No reaction product was detected on the periaxonal and outermost plasma membrane of Schwann cells and in the myelin sheath. In control tissue samples, the enzyme activity was almost completely inhibited by 10 mM ouabain, and no reaction was noted in medium without K+.
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PMID:Cytochemical study of ouabain-sensitive, K(+)-dependent p-nitrophenylphosphatase activity in guinea pig facial nerve. 820 12

Structure and function of the marginal cell in the stria vascularis were studied by freeze-fracture, cytochemistry and immunohistochemistry with special regard to the ion transport of potassium. Freeze-fracture showed that marginal cells were connected by tight junctions beneath the scala media K(+)-NPPase cytochemistry showed that Na+, K(+)-ATPase was abundant on the basolateral infoldings of the marginal cell. Immunohistochemistry of a rat Isk protein, which has a property of a potassium channel, revealed that the rat Isk protein was localized at the endolymphatic surface of the marginal cell. These findings supported the 'one-pump' theory (Offner et al. Hear Res 1987; 29: 117-24).
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PMID:Morphological aspects of transport of potassium ion in the marginal cell. 838 17

In previous papers, the isolation of brain soluble fractions able to modify neuronal Na+, K(+)-ATPase activity has been described. One of those fractions-peak I-stimulates membrane Na+, K(+)-ATPase while another-peak II-inhibits this enzyme activity, and has other ouabain-like properties. In the present study, synaptosomal membrane Na+, K(+)-ATPase was analyzed under several experimental conditions, using ATP or p-nitrophenylphosphate (p-NPP) as substrate, in the absence and presence of cerebral cortex peak II. Peak II inhibited K(+)-p-NPPase activity in a concentration dependent manner. Double reciprocal plots indicated that peak II uncompetitively inhibits K(+)-p-NPPase activity regarding substrate, Mg2+ and K+ concentration. Peak II failed to block the known K(+)-p-NPPase stimulation caused by ATP plus Na+. At various K+ concentrations, percentage K(+)-p-NPPase inhibition by peak II was similar regardless of the ATP plus Na+ presence, indicating lack of correlation with enzyme phosphorylation. Na+, K(+)-ATPase activity was decreased by peak II depending on K+ concentration. It is postulated that the inhibitory factor(s) present in peak II interfere(s) with enzyme activation by K+.
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PMID:An endogenous factor which interacts with synaptosomal membrane Na+, K(+)-ATPase activation by K+. 838 89

The epithelium covering the large intestinal lymphoid follicles in fetal and postnatal lambs was examined for potassium-dependent p-nitrophenyl-phosphatase (K(+)-NPPase), carbonic anhydrase, magnesium-dependent adenosine triphosphatase (Mg(2+)-ATPase) and acid phosphatase. Reactivities for these enzymes indicated a homogenous population of cells in the follicle-associated epithelium (FAE), distinct from the absorptive epithelium. There were essentially no differences in the enzyme reactivities of the large intestinal FAE between fetuses in late gestation and postnatal lambs. The FAE showed a weak reaction for K(+)-NPPase and a variable staining for Mg(2+)-ATPase and acid phosphatase. In contrast, the adjacent absorptive epithelium demonstrated strong reactions for these enzymes. Carbonic anhydrase gave a strong reaction at the luminal and apparent basolateral cell borders of the large intestinal FAE. This distribution of reactivity for carbonic anhydrase resembled that found in the ileal FAE. In absorptive epithelial cells, only the luminal cell border reacted strongly for carbonic anhydrase. Serial sections of large intestinal tissue showed a variation in the basolateral staining of FAE from one section to the next, a finding which suggested that the reaction may be associated with transcytosis. The lymphoid follicles and domes of the large intestine showed a variable granular pattern of carbonic anhydrase staining, which also suggested a dependence on epithelial transcytosis.
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PMID:Potassium-dependent p-nitrophenyl phosphatase and carbonic anhydrase reactivities suggest that lymphoid follicles in the large intestine of lambs are lined with a uniform type of epithelial cell distinct from the absorptive epithelium. 840 61

It is well-known that Na(+)-K(+)-ATPase plays an important role in active transportion of sodium (Na) and potassium (K) ions across the epithelium. This paper reports the ultrastructural localization of the K(+)-NPPase reflecting Na(+)-K(+)-ATPase activity in the guinea pig endolymphatic sac (ES) with the lead citrate one step method. The ultrathin sections viewed in the transmission electron microscope revealed that the reaction product was restricted to the cytoplasmatic side of the basolaterl plasma membranes of the ES epithelial cells. And the reactivity could be traced all the way up to the level of tight junctions close to the luminal aspect of the cells. On the other hand, the luminal plasma membrane of the epithelial cells showed no enzyme activity. Our findings suggest that the rich Na(+)-K(+)-ATPase enzyme activity is preferentially localized on the basolateral plasma of membrane of the ES epithelial cells. Possible physiological mechanism of Na(+)-K(+)-ATPase in the Na(+)-K+ ion transport of ES epithelial cells is discussed.
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PMID:[Ultracytochemical localization on Na(+)-K(+)-ATPase activity in the guinea pig endolymphatic sac]. 857 70

The post-natal development of the K(+)-dependent p-nitrophenylphosphatase (K-NPPase) activity of the Na, K-ATPase complex and its regulation by corticosteroids was studied in renal and intestinal epithelia of the rat using the p-nitrophenylphosphatecerium capture method. The distribution of the phosphatase was analysed in detail in the renal epithelia of the medullary thick ascending limb of Henle's loop and distal convoluted tubule and in the surface epithelial cells of the distal colon. The convoluted tubule and Henle's loop segments showed a stronger reaction for K-NPPase than the colon epithelium both in adult and young animals (suckling and weanling pups). The intensity of staining rose progressively in all three epithelia during early postnatal development and reached the highest levels during the weaning period and in adulthood. The most distinct change was observed between days 10 and 16. Adrenalectomy significantly reduced the density of the final reaction product in weanling and adult rats. Replacement hormone therapy of adrenalectomized weanling rats with the glucocorticoid dexamethasone restored the K-NPPase activity in the two renal epithelia, whereas the mineralocorticoid deoxycorticosterone acetate had no effect on the activity in the medullary thick ascending limb, a very slight effect in distal convoluted tubules, and a strong effect on the distal colon epithelial activity. The observed small effect of the mineralocorticoid in distal convoluted tubule activity may reflect a cross-over into glucocorticoid receptors. We conclude that the postnatal development of Na, K-ATPase is regulated by glucocorticoids in nephron epithelia and predominantly by mineralocorticoids in the surface enterocytes of the distal colon.
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PMID:Corticosteroid induction of renal and intestinal K(+)-dependent p-nitrophenylphosphatase in young and adult rats. 891 33

To provide the prerequisite for long-term study of the inner ear related to structural and functional integrity, tissue of stria vascularis with spiral ligament was isolated from Wistar rat cochleas and cultured using the explant-culture technique. The following culture media were used: EMEM with Hepes buffer, hydrocortisone (400 ng/ml), transferrin (5 micrograms/ml). triiodothyronine (10(-9) M), cholera toxin (10(-10) M), insulin (5 micrograms/ml), and epidermal growth factor (10 ng/ml). To characterize the cells growing out from the explant, immunofluorescence with cytokeratin (cytokeratin 18) and ultrastructural examination with SEM and TEM were performed. The marginal cell function was investigated by expression of Na+, K(+)-ATPase antisera against beta 2 subunit of rat Na+, K(+)-ATPase and P-NPPase. We were able to maintain the cultured cells for 3 weeks or more. Monolayered marginal cells were observed beyond 14 days in vitro and the expression of cytokeratin 18 was especially enhanced. The cultured marginal cells were almost identical to in vivo cells both as regards ultrastructural features and Na+, K(+)-ATPase activity. The present results suggest that the primary explant culture technique is a reliable in vitro model of strial marginal cells. However, establishment of the cell line is needed for long-term study.
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PMID:Establishment of primary cell culture from stria vascularis explants. Morphological and functional characterization. 897 11


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