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)

This paper reviews the principal effects of phenobarbital on biliary function. Phenobarbital administration is followed by an increase in bile flow. This is mainly due to an increase in the bile salt-independent fraction of canalicular bile flow possibly through an increase in canilicular Na+-K+ ATPase activity. In addition, bile salt excretion may be increased. This effect of barbiturates on choleresis appears to be independent of microsomal enzyme induction. Barbiturates increase the uptake, storage and excretion of various dyes, for example sulfobromophthalein. Phenobarbital increases bilirubin clearance by the liver; it enhances bilirubin-UDP-glucuronyl transferase activity; whether the influence on bilirubin clearance is related to the effect on the enzyme is unknown. The influence of phenobarbital on biliary lipids is markedly different from one species to the other. In the rhesus monkey and in the rat, the relative concentration of cholesterol is decreased; in the hamster it is increased, and in man it appears largely unaffected. These effects of phenobarbital have been utilized in the treatment of chronic unconjugated hyperbilirubinemia and of certain cholestatic syndromes. Phenobarbital alone has been useful, so far, in the treatment of cholesterol gallstones.
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PMID:Barbituates and biliary function. 12 85

Besides the Mg-ATPase, a Na,K-ATPase can be demonstrated in different fractions of smooth muscles of the A. carotis communis of the sheep. The highest activity of Mg-ATPase is observed in the heavy microsomal fraction. The Ca-ion may act as a complete substitute for the Mg-ion in the Mg-ATPase. The proportion of Na,K-ATPase is between 10 and 40%, depending on the preparative conditions used in the individual fractions. Fractionated salt treatment (LiBr, KC1, KBr) improved the assay of Na,K-ATPase but increased strength of the Tris-HC1-buffer considerably reduced its activity.
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PMID:Demonstration of a Mg-ATPase and a Na,K-ATPase from the arteria carotis communis of the sheep. 12 27

Recent work in our laboratory on the purification and characterization of the (sodium + potassium)-activated adenosinetriphosphatase (NaK ATPase) has been reviewed. Two enzymes have been purified, that from the rectal salt gland of the spiny dogfish, Squalus acanthias and that from the electric organ of the electric eel, Electrophorus electricus. The enzyme appears to consist of two catalytic subunits of molecular weight of about 95,000 and one glycoprotein with a molecular weight of about 50,000. The amino acid composition, N-terminal amino acids, and the carbohydrate composition of these subunits have been determined. The phospholipid composition of the holoenzyme has also been determined. The protein component shows very little variation with evolution, but the carbohydrate and phospholipid components show considerable variation. It has been possible to form vesicles from the purified enzyme from Squalus acanthias and to demonstrate the ATP-dependent, ouabain inhibitable, coupled uphill transports of Na+ and K+. The properties of these transports are very similar to those observed previously in intact erythrocytes or resealed erythrocyte ghosts with respect to asymmetries of binding sites, stoichiometries of Na+ and K+ transported, Na+-Na+ exchange, and K+-K+ exchange. It is concluded that the NaK ATPase is the molecular machine for effecting Na+ and K+ transport in the intact cell membrane.
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PMID:Purification and molecular properties of the (sodium + potassium)-adenosinetriphosphatase and reconstitution of coupled sodium and potassium transport in phospholipid vesicles containing purified enzyme. 12 29

Ethacrynic acid (EA) was injected to rats with functional nephrectomy after a control period of steady-state bile flow sustained by taurocholate infusion. Biliary clearance of [14C]mannitol was measured in order to estimate canalicular bile flow and bile salt-independent fraction (BSIF). After EA infusion, bile flow increased by 56%; bile salt excretion rate decreased by 10%; electrolyte excretion rates all increased, principally Na+ and K+. Mannitol clearance increased in parallel with bile flow. The BSIF increased. EA was excreted into bile as a metabolite identified as the cysteine adduct of EA; its excretion rate was linearly correlated with the increment in bile flow. The results are consistent with the hypothesis that the biliary excretion of an EA derivative results in an osmotic water flow increasing the canalicular BSIF. Since EA ia a Na+-K+-ATPase inhibitor, it is necessary to reconsider the relationship between secretion of canalicular BSIF and active Na+ transport mediated by the Na+-K+-ATPase system.
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PMID:Mechanism of ethacrynic acid-induced choleresis in the rat. 12 97

The (Na+ plus K+)-ATPase activities in salt gland homogenates increased 3- to 4-fold after saline treatment of ducks for 3 weeks. The ATPase was purified to a specific activity of 460 and 1015 mumol Pi/mg protein per h, respectively, in control and saline-treated ducks. The catalytic protein was identified on polyacrylamide electrophoresis gels by phosphorylating the enzyme with (32P)ATP. The molecular weight of the protein was estimated to be 98 000. The amount of catalytic unit increased commensurately with the enzyme activity after saline treatment. It is therefore concluded that the increased enzyme activity is due to a de novo enzyme synthesis and is not an activation effect. Phospholipid concentration in the salt gland tissue increased 1.7-fold after the saline treatment. Significant increases occurred in the percentage of the total phospholipids as phosphatidylserine and sphingomyelin. In the partially purified (Na+ plus K+)-ATPase preparation, the percentage composition of phosphatidylserine and phosphatidylethanolamine increased after saline treatment.
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PMID:Induction of the catalytic protein of (Na+ plus K+)-ATPase in the salt gland of the duck. 12 80

Ultrasonic treatment of microsome fraction or the preparation of partially purified Na+, K+-ATPase from cattle brain resulted in the formation of closed structures which immobilized rubidium and sodium ions and were easily discovered in electron microscope. Gradual release of bound rubidium ions was observed under the incubation of ultrasonic-treated membrane preparation in salt solutions. This process was activated by ATP. ATP-activated release of rubidium was observed only in the presence of sodium and was inhibited by ouabain. A hypothesis on the participation of sodium pump in the ion transport through membranes of artificial vesicles is discussed.
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PMID:[Properties of artificial vesicles from biological membranes]. 12 87

In the serum of two infant sisters with a congenital renal salt-losing syndrome, Na was rather low and K considerably increased. Even with Na levels of 126 mval/1, sodium was excreted in the urine. Creatinine and hippurate clearances were normal. Primary disturbances of the steroid metabolism were not detectable; plasma cortisol was normal, aldosterone and renin were compensatorily increased. Treatment with DOCA was unsuccessful. Whereas the first infant died (in another hospital), the second one throve well with high oral substitution of NaCl. There was no pathological findings other than a moderate hyperplasia of the juxtaglomerular apparatus, in a kidney biopsy. Except for minimal activity in the ascending limb of Henle's loop, there was no membrane bound Na, K-ATPase in the microdissected tubules. This finding most probably explains the renal salt loss, as this enzyme is necessary for the transcellular flow of sodium and potassium.
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PMID:Tubular Na, K-ATPase deficiency, the cause of the congenital renal salt-losing syndrome. 12 30

High concentrations of sulfolipids (four fractions having different hexose/sulfate ratio), intense enzyme activity (ATPase, oxoreductases) and evidence of mucines (staining with PAS and Alcian blue) in intercellular spaces were found in the lachrymal glands of Caretta caretta and Malaclemys terrapin adapted to sea water. In addition, the supranuclear region of the gland cells in Malaclemys terrapin is filled with mucin granules. These biochemical and histochemical observations indicate that these glands have a function in salt secretion in both species and are also consistent with a function of mucous secretion exclusively in Malaclemys terrapin. Limited signs of hypotrophy are not accompanied by changes in concentrations of sulfolipids in Malaclemys terrapin adapted to fresh water; only the reactions for enzyme activities are less intense. The mucous secretion is not affected, whereas, in correlation with changes in salt secretion, the change in ATPase activity is mot conspicuous. The correlations between the different components of the gland and salt secretion are compared with salt glands of birds and elasmobranchs.
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PMID:The sulfatides and some histochemical correlations of the lachrymal glands involved in salt secretion in Chelonia. 13 Nov 77

Sodium- and potassium-activated adenosine triphosphatase (NaK-ATPase) was purified from nasal salt glands of the duck (Anas platyrhynchos). Enzyme of specific activity 2,000 to 2,300 mumol of Pi/mg/hour was routinely obtained by sodium dodecyl sulfate treatment of a microsomal fraction of gland homogenate in the presence of 3 mM ATP followed by pelleting of the enzyme through a sucrose density gradient. Purified NaK-ATPase was stable for over 3 months at -20 degree. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography purified NaK-ATPase was shown to contain two polypeptide chains of molecular weight 94,000 and 60,000, the smaller of which was a glycoprotein. Purified enzyme of activity 2,300 mumol of Pi/mg/hour bound 3,600 pmol of ouabain/mg of enzyme protein. Reaction with [gamma-32P]ATP in the presence of Mg2+ and Na+ gave 7,025 pmol of acyl phosphate/mg of enzyme protein. The turnover number calculated from phosphorylation data was 5,460 min-1. Amino acid analysis of the polypeptide components of duck salt gland enzyme after separation by gel filtration chromatography in sodium dodecyl sulfate demonstrated strong compositional homology with highly purified NaK-ATPase preparations from other organs and species. The NH2-terminal amino acid of the 94,000-dalton component was glycine and of the 60,000-dalton component, alanine. With a combination of manual sequencing and automated Edman degradation, the NH2-terminal amino acid sequence of the 94,00-dalton catalytic subunit was found to be Gly-Arg-Asn-Lys-Tyr-Glu-Thr-Thr-Ala-()-Ser-Glu.
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PMID:Sodium- and potassium-activated adenosine triphosphatase of the nasal salt gland of the duck (Anas platyrhynchos). Purification, characterization, and NH2-terminal amino acid sequence of the phosphorylating polypeptide. 13 47

Certain euryhaline teleosts can tolerate media of very high salinity, i.e. greater than that of seawater itself. The osmotic gradient across the integument of these fish is very high and the key to their survival appears to be the enhanced ability of the gill to excrete excess NaCl. These fish provide an opportunity to study morphological and biochemical aspects of transepithelial salt secretion under conditions of vastly different transport rates. Since the cellular site of gill salt excretion is believed to be the "chloride cell" of the branchial epithelium and since the enzyme Na,K-ATPase has been implicated in salt transport in this and other secretory tissues, we have focused our attention on the differences in chloride cell structure and gill ATPase activity in the variegated pupfish Cyprinodon variegatus adapted to half-strength seawater (50% SW), seawater (100% SW), or double-stregth seawater (200% SW). The Na,K-ATPase activity in gill homogenates was 1.6 times greater in 100% SW. When 50% SW gills were compared to 100% SW gills, differences in chloride cell morphology were minimal. However, chloride cells from 200% SW displayed a marked hypertrophy and a striking increase in basal-lateral cell surface area. These results suggest that there are correlations among higher levels of osmotic stress, basal-lateral extensions of the cell surface, and the activity of the enzyme Na,K-ATPase.
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PMID:Teleost chloride cell. I. Response of pupfish Cyprinodon variegatus gill Na,K-ATPase and chloride cell fine structure to various high salinity environments. 13 50


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