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)

A pronounced effect of concanavalin A (Con A) upon activity of ecto-5'-nucleotidase of intact C6 glioma cells in culture has been demonstrated. A near linear rate of decrease in 5'-nucleotidase activity was observed upon treatment with concentrations of Con A up to 0.25 muM. Nonspecific phosphatase activity and Ca2+-dependent ATPase activity were not inhibited by Con A treatment of the cells. Of the total 5'-nucleotidase activity of C6 cells (Vmax = 5.0 mumol of Pi liberated/mg of cell protein/hour), approximately 20% still remained after treatment with high concentrations of Con A. The inhibitory effect of Con A operated to reduce substantially Vmax for ecto-5'-nucleotidase. Inhibition was reversed by briefly incubating the Con A-treated cells with alpha-methyl-D-glucoside, or alpha-methyl-D-mannoside, the later being more effective. These findings suggest that a relatively specific, reversible, inhibition of ecto-5'-nucleotidase results from Con A binding to the surface of the intact cultured mammalian cells.
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PMID:Concanavalin A inhibition of ecto-5'-nucleotidase of intact cultured C6 glioma cells. 12 59

The influence of the mode of preparation upon some of the characteristics of white adipose tissue plasma membranes and microsomes has been reported. Plasma membrane fractions prepared from mitochondrial pellet were shown to have higher specific activities of (Mg2+ + Na+ + K+)-ATPase than plasma membranes originating in crude microsomes. Isolation of fat cells by collagenase treatment was found to result in a decrease in specific activity of the plasma membrane enzymes; in plasma membranes prepared from isolated fat cells, the specific activity values obtained for (Mg2+ + Na+ +k+)-ATPase and 5'-nucleotidase were only 42% and 6.3% respectively of those obtained in plasma membranes prepared from whole adipose tissue. Purification of whole adipose tissue crude microsomes by hypotonic treatment caused extensive solubilization of the endoplasmic reticulum marker enzymes, NADH oxidase and NADPH cytochrome c reductase. The lability of endoplasmic reticulum marker enzymes, however, was found to be greatly diminished in the preparations from isolated fat cells. The possibility that NADH oxidase and NADPH cytochrome c reductase activities found in the plasma membranes are microsomal enzymes adsorbed by the plasma membranes is discussed. The peptide patterns as well as the NADH oxidase and NADPH cytochrome c reductase activity patterns of plasma membranes and purified microsomes were compared by means of sodium dodecyl sulfate or Triton X-100 polyacrylamide gel electrophoresis.
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PMID:Comparison of plasma membranes and endoplasmic reticulum fractions obtained from whole white adipose tissue and isolated adipocytes. 12 89

In the present paper the mechanism of the adenosine formation by a mixture of nerve ending and transmitter granula fractions was invesitgated. The adenosine formation in vivo is only possible via the whole degradation chain ATP - ADP - AMP - adenosine. The enzymes involved are ATPases, adenylate kinase and 5'-nucleotidase. The ATPase and adenylate kinase effectors Ca++ and Mg++ can be regarded as trigger ions switching on and off the degradation chain. The adenylate kinase represents a key enzyme within the whole chain. In the ion-activated state a non-inhibited adenosine formation was observed, when the initial ATP concentration amounted to less than 0,1 muMol per mg synaptosomal membrane protein. Under these conditions the whole chain velocity is mainly dependent on the 5'-nucleotidase concentration, because ATPases and adenylate kinase remove the nucleotidase inhibitors ATP and ADP spontanously. The conditions for the optimal velocity of the adenosine formation at the synaptic membrane in vivo in all probability are present. A hypothesis for the mechanism of the synaptic adenosine formation in vivo was developed. The importance of this process in respect to the synaptic transmission was discussed.
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PMID:[Mechanism of synaptosomal degradation of ATP in connection with involvement of adenosine in the transmission process]. 12 26

Liver plasma membranes were isolated from regenerating rat livers between 20 h and 10 days after partial hepatectomy in order to study the effect of partial hepatectomy on some membrane enzyme activities. Mg2+-ATPase (EC 3.6.1.4) activity, but not (Na+ + K+)-ATPase activity, decreased slightly at 2 days, whereas leucyl beta-naphthylamidase (EC3.4.1.1) and 5'-nucleotidase (EC3.1.3.5) activities increased considerably at 1-2 and 3-5 days, respectively. These changes were not parallel to a sharp increase in mitotic activity of liver cells which occurred at 36 h.
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PMID:Changes in some marker enzyme activities of liver plasma membranes during regeneration after partial hepatectomy in rats. 13 Jan 67

The plant lectin concanavalin A (Con A) specifically inactivates the 5'-nucleotidase of a plasma membrane-enriched fraction from lactating mammary gland. The lectin also causes an activation of the membrane Mg++-ATPase, but does not affect galactosyltransferase or alkaline phosphatase. The enzyme perturbations are prevented by alpha-methylmannoside, an inhibitor of Con A binding, indicating that specific binding to carbohydrate structures rather than nonspecific protein-protein interaction is involved. Solubilization of the 5'-nucleotidase in detergents (0.2% Triton X-100 or 1% deoxycholate) does not prevent Con A inactivation, indicating that incorporation into the membrane structure is not a requirement for the Con A effect. the results suggest that Con A inactivates the 5'-nucleotidase by a direct interaction with the enzyme and that this enzyme is a Con A receptor site on the surface of mammary cells.
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PMID:Concanavalin A perturbation of membrane enzymes of mammary gland. 13 May 16

Two highly lead-sensitive ATPases, Na+,K+-ATPase and adenylate cyclase, can be demonstrated cytochemically by the lead precipitation technique in briefly prefixed tissue, provided that the free Pb2+ concentration in the incubation medium is kept below 0.1 mM by a heavy metal chelator. Under conditions suitable for Na+,K+-ATPase activity precipitation of final reaction product (lead phosphate) at the sarcolemma of cardiac muscle is abolished by 0.1-1mM ouabain. In contrast, reaction product deposition at the intramuscular part of the plasma membrane and at intracellular sites is not noticeably affected by the glycoside. These findings indicate either that the sarcolemma is the exclusive location of Na+,K+-ATPase in cardiac muscle or that the presence of the enzyme at other loci is masked by active Na+,K+-independent, ouabain resistant ATPases. Under conditions favoring adenylate cyclase activity, precipitation by Pb2+ of orthophosphate derived, with the help of added cyclic nucleotide phosphodiesterase and 5'-nucleotidase, from cyclic AMP formed from adenylyl imidodiphosphate (AMP-PNP) is seen after prolonged incubation in myocardial cells along the entire course of the plasma membrane and also at the transverse tubules and is particularly intense at the tight junction regions of the intercalated disks. Ouabain has no effect on these reactions. Reaction product deposition is also observed at the sarcolemma in red skeletal muscle and at the terminal cisternae of the sarcoplasmic reticulum in white skeletal muscle, where the reaction is intensified by adrenaline. Sarcoplasmic reticulum of cardiac and of red skeletal muscle exhibits only relatively weak staining attributable to cyclic AMP formation. These observations are in agreement with the results of tissue fractionation studies according to which the plasma membrane is the chief site of adenylate cyclase in heart and in red, but not white skeletal muscle.
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PMID:Cytochemical studies on sarcolemma: Na+, K+-adenosine triphosphatase and adenylate cyclase. 13 Jun 56

An isolation procedure for synaptic plasma membranes from whole chick brain is reported that uses the combined flotation-sedimentation density gradient centrifugation procedure described by Jones and Matus (Jones, D. H. and Matus, A. I. (1974) Biochim. Biophys. Acta 356, 276-287) for rat brain. The particulate of the osmotically shocked and sonicated crude mitochondrial fraction was used for a flotation-sedimentation gradient step. Four fractions were recovered from the gradient after 30 min centrifugation. The fractions were identified and characterized by electron microscopy and by several markers for plasma membrane and other subcellular organelles. Fraction 2 was recovered from the 28.5-34% (w/v) sucrose interphase and contained the major part of the activities of the neuronal plasma membrane marker enzymes. The specific activities of the (Na+ +K+)-activated ATPase (EC 3.6.1.3), acetylcholinesterase (EC 3.1.1.7) and 5'-nucleotidase (EC 3.1.3.5) were, respectively, 4.5, 2.0 and 1.2 times higher than in the homogenate. However, Fraction 2 also contained considerable amounts of activities of putative lysosomal and microsomal markers in addition to lower amounts of mitochondrial and myelin markers. Although no prepurification of synaptosomes from the crude mitochondrial fraction was performed, the synaptic plasma membranes obtained showed many properties analogous to similar preparations from rat brain described in recent years.
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PMID:Isolation and partial characterization of chick brain synaptic plasma membranes. 13 94

The relationship between bile salt-independent canalicular flow and ATPase activity in liver plasma membranes (LPM) enriched in bile canaliculi, was studied in control, hyperthyroid, and hypothyroid rats. Canalicular bile production was significantly increased in hyperthyroid rats (3.19 +/- 0.23 mul/min per g liver) compared to controls (2.27 +/- 0.24 mul/min per g liver), while it diminished in hypothyroid animals (1.58 +/- 0.17 mul/min per g liver). Although bile salt excretion was also increased in hyperthyroid animals (62.4 +/- 13.3 vs. 41.2 +/- 8.4 nmol/min per g liver), the stimulation in canalicular secretion was primarily related to enhancement of the bile salt-independent fraction of flow (2.47 mul/min per g liver in hyperthyroid rats vs. 1.67 mul/min per g liver in controls). LPM Na+, K+-ATPase activity doubled in hyperthyroid animals (21.5 +/- 5.8 vs. 10.7 +/- 3.1 mumol Pi/mg protein per h) while Mg++-ATPase activity remained unchanged and 5'-nucleotidase activity increased to a small but significant extent. In hypothyroid rats, bile salt excretion remained unchanged from control values so that the reduced secretion was entirely secondary to an inhibition of bile salt-independent secretion (1.19 mul/min per g liver). Na+, K+-ATPase activity in the LPMs from hypothyroid animals decreased by nearly 50% (5.4 +/- 1.6 mumol Pi/mg protein per h), although comparable reductions in the specific activity of Mg++-ATPase and 5'-nucleotidase were also observed. Administration of L-thyroxine to hypothyroid animals restored both bile salt-independent canalicular secretion and membrane enzymes to control values within 2 and 4 days, respectively. Sodium dodecyl sulfate gel electrophoresis demonstrated no significant changes in LPM protein fractions from any of the treatment groups. These studies indicate that thyroid hormone has a parallel effect on bile salt-independent canalicular secretion and LPM Na+, K+-ATPase activity, supporting the hypothesis that Na+ transport and Na+, K+-ATPase may be determinants of bile salt-independent canalicular flow.
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PMID:The effect of thyroid hormone on bile salt-independent bile flow and Na+, K+ -ATPase activity in liver plasma membranes enriched in bile canaliculi. 13 19

The properties of a Ca2+ activated adenosine triphosphatase shown to be present in homogenates of purified rat peritoneal mast cells were investigated. The enzyme was activated by Ca2+, Mg2+, and to a lesser extent by Mn2+ and Co2+. Ca2+ alone was necessary for full activity and the further addition of Mg2+ did not have any effect. The chelating agents EGTA (ethanedioxybis(ethylamine)tetra-acetate) and EDTA completely inhibited the reaction. The pH optimum was 7.8. Reduced glutathione, cysteine, dithiothreitol, N-ethylmaleimide, urea, ADP, NaF, increasing ionic strength and Triton X-100 all inhibited the reaction. On subcellular fractionation of mast-cell homogenates by density-gradient centrifugation, the distribution of Ca2+ activated adenosine triphosphatase resembled that of 5'-nucleotidase, but differed from that of the other markers used, suggesting localization in the plasma membrane. Further experiments indicated that the enzyme is present on the external surface of the plasma membrane.
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PMID:Characterization of calcium-ion-activated adenosine triphosphatase in the plasma membrane of rat mast cells. 13 82

The Wachstein-Meisel ATPase histochemical method has been previously used to demonstrate the ultrastructural localization of this enzyme in both whole liver and isolated plasma membranes following fixation in glutaraldehyde. In the present study biochemical assay, of liver plasma membrane enzymes following fixation in cold 2.5% glutaraldehyde showed that approximately 40% of Mg2+-ATPase, but only 4% of (Na+-K+)-ATPase activity remained in membranes from either control or ANIT-treated rats. In addition, 5'-nucleotidase activity was almost abolished by fixation. The present results indicate that the Wachstein-Meisel method, when applied to biliary canaliculi, can reliably be used to demonstrate the ultrastructural, histochemical localization of Mg2+-ATPase but not that of (NA+-K+)-ATPase. Furthermore, the method permits a valid comparison to be made of the relative Mg2+-ATPase activity in normal and chemically damaged biliary canaliculi.
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PMID:Liver plasma membrane enzyme activities following glutaraldehyde fixation. 13 43


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