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)

An ATPase stimulated by HCO-3ions and other oxybases and inhibited by SCN- has been found in main excretory duct of rat submaxillary gland, a tissue, capable of actively secreting HCO-3ions. No such ATPase was found in the rabbit duct, which normally does not secrete HCO-3. The HCO-3ATPase was localized in the plasma membrane fraction of the homogenate, as evidenced by the marker 5'nucleotidase. The activities of the HCO-3ATPase increased in metabolic alkalosis and decreased in metabolic acidosis in parallel to secretion of HCO-3 and K+ ions by the rat salivary duct epithelium. In renal cortex tissue, where HCO-3 is actively reabsorbed respectively H+ is secreted, there was also found a parallel change in the activity of the HCO-3ATPase and the rate of active H+ secretion. These findings provide further evidence that the membrane-bound HCO-3ATPase is involved in active H+/HCO-3 transport. The HCO-3ATPase is not only stimulated by HCO-3 but also by other non transportable oxybases, a finding which indicates H+ rather than HCO-3 being the actively transported component of the buffer system. Small concentrations of K+ ions decrease the Km for HCO-3 and thus yield stimulation of the HCO-3-ATPase. Thport changing in parallel with that of H+/HCO-3 may be taken as indicative for a coupled K+-H+-exchange mechanism to which the HCO-3ATPase is linked.
Curr Probl Clin Biochem 1976
PMID:The role of HCO3-stimulated ATPase in buffer transport. 1 63

We described a micromethod for determining serum triglycerides (triacylglycerols) with the centrifugal analyzer. This technique is based on the procedure of Bublitz and Kennedy [J. Biol. Chem. 211, 951 (1954)]. The enzymic hydrolysis requires 10 min at 30 degrees C. Twenty-six serum triglyceride assays can be done in about 30 min. Concentration and absorbance are linearly related up to 5.0 mmol/liter, but higher concentrations can be assayed by changing conditions slightly. Day-to-day reproducibility for the method was satisfactory (CV, 2.7 to 8.4%). Comparison of this method and two other methods for triglycerides, the automated Hantzsch condensation method and a commercial enzymic method (Calbiochem), gave correlation coefficients of 0.976 and 0.990, respectively. Results are unaffected by the presence of endogenous serum ADP, pyruvic acid, phosphatases, or ATPase.
Clin Chem 1977 Feb
PMID:Ultraviolet spectrometry of serum triglycerides by a totally enzymic method adapted to a centrifugal analyzer. 1 84

Current information is reviewed on the mechanism of secretion in small intestine, including how it is altered by cyclic 3',5'-adenosine monophosphate and on the structures and properties of cholera and both heat-labile and heat-stable Escherichia coli enterotoxins. Two separate active ion transport processes are altered by cyclic 3',5'-adenosine monophosphate: 1) coupled absorption of NaCl is inhibited in villus cells and 2) active anion secretion is stimulated, probably in crypt cells. Cholera and heat-labile E. coli toxins exert their secretory effect by stimulating intestinal mucosal adenylate cyclase. This stimulation results from the A1 subunit catalyzed transfer of adenosine diphosphate ribose from NAD to a membrane-bound guanosine triphosphatase, thereby inhibiting the enzyme, which normally represses adenylate cyclase. Heat-stable E. coli enterotoxin stimulates intestinal mucosal guanylate cyclase, which appears to be the basis for its enterotoxicity.
Am J Clin Nutr 1979 Jan
PMID:Mechanisms of action of cholera and Escherichia coli enterotoxins. 3 66

The localization of gamma-glutamyltransferase activity in guinea pig liver was studied after subcellular fractionation. The enzyme activity was essentially connected with plasma membranes whereas only low activity was found in the endoplasmic reticulum. A similar activity distribution was demonstrated for 5'-nucleotidase. Highest specific activity of gamma-glutamyltransferase was found in plasma membranes enriched in bile canaliculi. In this fraction the specific activity was 35 times greater than the specific activity of the total homogenate, a value similar to the relative specific activity of (Na+,K+)-ATPase. More than 90% of the total gamma-glutamyltransferase activity in guinea pig liver was connected with parenchymal cells and the enzyme seemed to have an outside orientation. Animals treated with phenobarbital showed moderate increased in gamma-glutamyltransferase activity in serum and liver, whereas high activities were found in most bile samples. No particular liver subfraction showed substantial accumulation of gamma-glutamyltransferase activity. The present findings do not support the suggested use of serum gamma-glutamyltransferase measurements as a direct index of "microsomal enzyme induction".
Clin Chim Acta 1979 Jun 01
PMID:Subcellular localization of gamma-glutamyltransferase activity in guinea pig liver. Effect of phenobarbital on the enzyme activity levels. 3 6

There is evidence that membrane proteins can serve as the functional units of ionic transport in biological membranes. Laser Raman spectroscopy has been used to probe specific molecular interactions inside two models of transport membrane proteins, valinomycin and gramicidin A. Conformational changes of these molecules, as well as specific interactions with ions, can be detected and may help elucidate how membrane transport proteins such as Na+ minus K+ ATPase and rhodopsin function. Resonance Raman spectroscopy has also been used to study conformational changes and protein-chromophore interactions in rhodopsin, the membrane protein that acts as the primary unit of visual excitation in the eye.
Am J Clin Pathol 1975 May
PMID:Models of ionic transport in biological membranes. Raman spectroscopy as a probe of valinomycin, gramicidin A', and rhodopsin conformations. 4 37

The effect of ouabain, a specific sodium-potassium dependent adenosine triphosphatase (Na+-K+-ATPase) inhibitor, on antigen-induced histamine release was studied using guinea pig lung fragments sensitized in vitro with rabbit antibodies against bovine serum albumin. Histamine was assayed spectrofluorometrically. When sensitized tissue had been preincubated with ouabain (less than or equal to 1.0 x 10(-4) M) for 10 min prior to antigenic challenge, release of histamine was significantly inhibited (maximum 54%, p less than 0.001, N=9, paired t test). The most significant inhibition was obtained near the optimal concentration of antigen. The inhibition was dependent on the length of preincubation (less than or equal to 20 min), and was partially reversible upon washing the tissue removing the ouabain. Ouabain did not seem to prolong the duration of the histamine release process. Increase in potassium ion (less than or equal to 1.1 x 10(-2)M) inhibited the histamine release and had additive effects to ouabain action. Dibutyryl cyclic AMP (less than or equal to 5 x 10(-3) M), which could enhance the release, strongly antagonized the inhibition. Glucose removal from the medium did not abolish the ouabain effect. The results seem to indicate that immunologic release of histamine is under the influence of the membrane Na+-K+-ATPase activity.
J Allergy Clin Immunol 1976 May
PMID:Inhibition of antigen-induced histamine release by ouabain. 5 30

Ethacrynic acid, a known inhibitor of both Na+--K+ and Mg2+-activated ATPases, effectively inhibits histamine release from antigen-challenged human basophils in vitro. Ouabain, an inhibitor specific for Na+--K+-activated ATPases, shows no effect upon the quantity of histamine released from the antigen-challenged basophils. Ethacrynic acid also effectively inhibits Ca2+--ionophore A23187-induced release, implying it inhibits the Ca2+-dependent secretory stage of the histamine-release process. Inhibition of ATPases and histamine release by ethacrynic acid both require the presence of the olefinic bond in the ethacrynic-acid molecule. Possible utilization of analogues of ethacrynic acid as anti-allergic drugs and as a device to investigate the ATPase system of histamine-releasing cells is suggested.
Clin Exp Immunol 1977 Sep
PMID:Blocking of histamine release from human basophils in vitro by the ATPase inhibitor, ethacrynic acid. 7 37

A crude plasma membrane fraction from the homogenate of purified rat mast cells demonstrates a high degree of Ca2+-dependent and Mg2+-dependent adenosine triphosphatase (ATPase) activity. The microsomal and mitochondrial fractions show negligible amounts of the Ca2+ and Mg2+-activated ATPases. The broad ATPase inhibitor, ethacrynic acid, effectively blocks the mast cell ATPase activity while ouabain demonstrates little inhibitory effect. Correspondingly, ethacrynic acid inhibits histamine release from antigen-challenged mast cells while ouabain does not. Both ATPase inhibition and histamine release inhibition by ethacrynic acid require the presence of the olefinic bond in the ethacrynic acid molecule.
Clin Exp Immunol 1977 Oct
PMID:Ethacrynic acid inhibitable Ca2+ and Mg2+-activated membrane adenosine triphosphatase in rat mast cells. 7 76

As different structural states of the Na+-K+-ATPase (EC 3.6.1.3) may lead to a changed reactivity to antibodies, the influence of different ligands on the reaction between highly purified membrane-bound Na+-K+-ATPase and specific antibodies was investigated. The antigen antibody reaction was registered by measuring the antibody inhibition of Na+-K+-ATPase activity. It was found that Na+ decreased and K+ increased the antibody inhibition of the Na+-K+-ATPase activity of the membrane-bound enzyme if both Mg++ and ATP were present during the antigen antibody reaction. These effects were not observed if ATP was replaced by ADP or by the ATP analog adenylyl (beta-gamma-methylene) diphosphonate. If a solubilized enzyme preparation with the same specific activity was used the effects of Na+ or K+ which were demonstrated in the membrane-bound enzyme could not be detected. The study suggests that the Na+-K+-ATPase structure is altered by Na+ and K+, provided Mg++ and specifically the nucleotide ATP are also present. These structural changes are likely to occur during Na+-K+-transport and do not seem to be necessarily linked to the Na+, K+ and Mg++ stimulated ATP splitting of the enzyme.
Curr Probl Clin Biochem
PMID:Immunological characterization of Na+ and K+ mediated structural states of rat kidney Na+-k+-ATPase. 8 Mar 2

1. The renal handling of purified human immunoglobulin light chain has been studied with an isolated perfused rat kidney preparation. 2. Human immunoglobulin light chain was freely filtered and largely reabsorbed. Fractional reabsorption was characteristic for each of four light chains and varied between 56% and 86%. No renal tubular maximum for human light chain was obtained. 3. Light chains at concentrations up to 10 times those seen in human myeloma were without effect on glomerular filtration rate or sodium and potassium reabsorption in experiments lasting up to 2 h. 4. Filtered and reabsorbed light chain returned ultimately to the perfusion medium, indicating a unique property of the tubular handling of this protein. None of the inhibitors tested (ouabain, frusemide, acetazolamide, probenicid) influenced light chain reabsorption. 5. The results are taken to indicate that light chain reaches the site of the transport enzyme, Na+,K+-dependent ATPase, at concentrations which vary with the nature of the light chain. This may provide a mechanism for renal damage in patients with myeloma, after prolonged exposure.
Clin Sci (Lond) 1979 Jul
PMID:Characteristics of renal handling of human immunoglobulin light chain by the perfused rat kidney. 8 25


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