Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.5 (5'-nucleotidase)
 3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A mouse monoclonal antibody to rat 5'-nucleotidase (5N 4-2 McAb) was used in the direct anti-determinant rosetting reaction (DARR) to demonstrate the ecto-5'-nucleotidase molecule in preparations of rat lymphocytes. Results indicated that 35.5 +/- 7.5% of peripheral blood lymphocytes (PBL), 37.3 +/- 4.8% of lymph node cells (LN) and 37.0 +/- 8.5% of spleen lymphocytes expressed the 5N 4-2 antigen. Depletion studies and mixed rosetting reactions (MRR) showed that the 5N 4-2 antigen was mainly expressed on rat T lymphocytes rather than on B lymphocytes: In fact 59.6 +/- 3.2% (in PBL), 76.5 +/- 0.6% (in LN) and 67.1 +/- 1.3% (in spleen) of T lymphocytes exhibited the 5N 4-2 antigen compared to only 26.5 +/- 2.6% (in PBL), 34.0 +/- 2.1% (in LN) and 46.1 +/- 12.0% (in spleen) of B lymphocytes. As expected a strong association was found between the expression of 5N 4-2 antigen and 5'-nucleotidase enzyme activity on lymphocytes. Both 5N 4-2 positive cells and enzyme activity were preferentially exhibited in the T lymphocyte subpopulation, and 92% of the enzyme activity was observed in a 5N 4-2 antigen positive subpopulation.
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PMID:Detection of ecto-5'-nucleotidase on rat B and T lymphocyte subpopulations using a monoclonal antibody in rosetting reactions. 304 Aug 65

It is now well established that human lymphoblastoid cell lines showing immaturity characters display ecto-5'-nucleotidase activities lower than normal levels. A recent paper (Sun, A.S., Holland, J.F. and Ohnuma, T. (1983) Biochim. Biophys. Acta 762, 577-584) mentioned that this phenomenon resulted from the presence of a 5'-nucleotidase inhibitor in these cell lines. We demonstrate here that the use of 5'-[3H]AMP as a substrate, and inadequate analysis of the products formed, led them to a misinterpretation. [3H]Adenosine derived from 5'-[3H]AMP hydrolysis was further transformed into [3H]inosine by the adenosine deaminase activity of the leukemic cell lines tested; [3H]inosine was precipitated with the excess substrate and was not taken into account in the ecto-5'-nucleotidase determination, which led the authors to confuse this adenosine deaminase activity with a 5'-nucleotidase inhibitor. We did not observe 5'-nucleotidase inhibition by leukemic cell cytosol when convenient assay methods were used and showed that the presence of such an inhibitor remains to be established.
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PMID:The proposed 5'-nucleotidase inhibitor in human leukemic cells is an artefact. 608 22

Specific assays for 5'-nucleotidase, adenosine diphosphatase (ADPase) and Mg2+-dependent adenosine triphosphatase (Mg2+-ATPase) have been optimized for human lymphocytes and their subcellular localizations determined by sucrose density gradient centrifugation. 5'-Nucleotidase was localized solely to the plasma membrane of the lymphocyte. ADPase activity has been shown to have a dual localization to the plasma membrane and mitochondria, whilst Mg2+-ATPase was mainly located in the mitochondria. No [Na+,K+] activated Mg2+-dependent ATPase could be measured in these cells. We have confirmed the striking decrease in the specific activity of 5'-nucleotidase activity in lymphocytes from patients with common variable primary hypogammaglobulinaemia. In contrast, the specific activities of ADPase and Mg2+-ATPase showed no alteration in lymphocytes from the patient group when compared to controls. Thus the deficiency of ecto-5'-nucleotidase in the lymphocytes of patients with hypogammaglobulinaemia is a highly selective defect in purine metabolism.
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PMID:Studies on the kinetic properties and subcellular localization of adenine nucleotide phosphatases in peripheral blood lymphocytes from control subjects and patients with common variable primary hypogammaglobulinaemia. 612 80

The relative cytotoxicity of 9-beta-D-arabinofuranosyladenine and 9-beta-D-arabinofuranosyladenine 5'-monophosphate (ara-AMP) were compared using wild-type and adenosine kinase (AK)-deficient baby hamster kidney somatic cell mutants. The cytotoxicity of ara-AMP to baby hamster kidney cells was dependent on the presence of AK activity since AK-deficient mutants were resistant to ara-AMP. On an equimolar basis, ara-AMP was consistently less cytotoxic than was 9-beta-D-arabinofuranosyladenine to wild-type and AK-deficient baby hamster kidney mutant cells. These findings are consistent with the common view that ara-AMP molecules do not enter mammalian cells as an intact nucleotide. Presumably, ara-AMP molecules were hydrolyzed by the nonspecific phosphatases and 5'-nucleotidase found in the serum or by the ecto-5'-nucleotidase on the outer surface of the membrane and only enter the mammalian cells as 9-beta-D-arabinofuranosyladenine.
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PMID:Relative cytotoxicity of 9-beta-D-arabinofuranosyladenine and 9-beta-D-arabinofuranosyladenine 5'-monophosphate. 616 44

Several agents that react with plasma membranes, namely the native lectins concanavalin A, Ricinus communis agglutinin, and wheat germ agglutinin, the modified lectin succinyl concanavalin A, and sodium meta-periodate, inhibited the ecto-5'-nucleotidase of intact guinea pig granulocytes. Stimulation of the enzyme was not observed at any lectin concentration. Inhibition by native lectins could be blocked or reversed by appropriate competing hapten sugars. In the case of concanavalin A, reversal could be achieved at 37 degrees C, but not at 5 degrees C. When lectins were used in combination with each other, the effects were found to be largely independent. However, when concanavalin A and R. communis agglutinin were applied together, complications arose because the former lectin binds to the latter as well as to the cell surface. To avoid some of the complexities inherent in studying intact cell 5'-nucleotidase and to gain additional information about the system, two broken cell enzyme preparations were also examined. The enzyme of plasma membrane-enriched fractions was inhibited by all five agents mentioned above. 5'-Nucleotidase solubilized in sodium deoxycholate was inhibited by the four lectins but stimulated by periodate. The effects of the surface modifiers on kinetic data for all three enzyme preparations are consistent with the hypothesis that direct interactions with the enzyme molecule give rise to changes in Vmax; interactions at membrane sites other than 5'-nucleotidase itself could cause increases in apparent Km values. Effects of interactions of ectoenzymes with plant lectins may serve as models for phenomena that result from cell-cell interactions or from interactions of animal cells with lectin-like components of the cellular environment.
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PMID:Effect of surface modifiers on an ectoenzyme: granulocyte 5'-nucleotidase. 624 42

The effect of ethanol on an enzyme system within an intact functional plasma membrane has been studied using neural cells grown in culture. Rat C6 glioma cells in mono-layer culture were treated acutely or chronically with 100 mM ethanol and the effect of this exposure on the activity of ecto-5'-nucleotidase was determined. Acute exposure led to an increase in enzyme activity with maximum stimulation occurring at concentrations of 100 - 400 mM ethanol. Chronic treatment of cells with 100 mM ethanol for 4 - 8 days also caused an increase in ecto-5'-nucleotidase activity. Both the acute and chronic ethanol-induced stimulation of enzyme activity was completely reversible by removing the ethanol; the acute effects reversed immediately, whereas the chronic effects required several hours. The addition of Concanavalin A demonstrated that the effects on enzyme activity of both chronic and acute exposure to ethanol were blocked by modification of the external cell surface. The effect of chronic exposure to 100 mM ethanol was further localized to an action on the plasma membrane by studies which showed chronic exposure to have no effect on the intracellular 5'-nucleotidase activity. Furthermore, the occurrence of pharmacological tolerance to acute ethanol was observed in this plasma membrane system following chronic treatment of C6 cells with 100 mM ethanol. These findings are consistent with the hypothesis that mammalian neural cells can adapt to the chronic presence of ethanol through changes in their plasma membrane.
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PMID:Effect of ethanol on neural cells grown in culture: interaction with plasma membrane ecto-5'-nucleotidase activity. 625 Mar 29

The growth of cultured leukemic T-lymphocytes is readily inhibited by deoxynucleosides, particularly thymidine, deoxyguanosine, and deoxyadenosine. By contrast, Epstein-Barr virus-transformed B-lymphocytes are relatively resistant to deoxynucleosides. Growth inhibition correlates with the development of high deoxyribonucleoside triphosphate pools following exposure to deoxynucleosides. Leukemic T-lymphocytes are deficient in ecto-5'-nucleotidase (5'-ribonucleotide phosphohydrolase, EC 3.1.3.5) activity, and it has been postulated that deficiency of this enzyme decreases the capacity of these cells to degrade deoxyribonucleotides, rendering them sensitive to deoxynucleosides. We find that the sensitivity of cultured null-type leukemic lymphocytes to growth inhibition of deoxynucleosides is similar to that of T-cells. However, the null cells contain normal levels of ecto-5'-nucleotidase. We infer that ecto-5'-nucleotidase deficiency does not have a central role in determining the deoxynucleoside sensitivity of leukemic lymphocytes.
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PMID:Sensitivity of leukemic human null lymphocytes to deoxynucleosides. 625 63

In an attempt to further define the site of myocardial adenosine formation, isolated guinea pig hearts were perfused with potent inhibitors of 5'-nucleotidase [alpha, beta-methylene adenosine 5'-diphosphate (AOPCP)] and of nucleoside transport [4-nitrobenzyl thioinosine (NBMPR)]. AOPCP (50 microM) inhibited the activity of cardiac ecto-5'-nucleotidase by 85% but did not influence the release of adenosine, inosine, and hypoxanthine formed at an accelerated rate by the heart during hypoxic perfusion (30% O2). In contrast, NBMPR (5 microM) diminished the hypoxia-induced release of adenosine and its degradatives and greatly potentiated the increase of myocardial tissue levels of respective purine compounds. Studies carried out with 5'-deoxyadenosine, an adenosine derivative that is not metabolized, indicate NBMPR to inhibit both uptake and release of adenosine in the isolated heart and in human erythrocytes. Cell fractionation studies on guinea pig ventricular muscle revealed that 5'-nucleotidase, though mainly associated with the membrane fraction, is also found in the cardiac cytosol (200,000-g supernatant), exhibiting a different substrate specificity. Furthermore, S-adenosylhomocysteine hydrolase as well as adenosine kinase and adenosine deaminase proved to be exclusively present in the cytosolic fraction. Our findings suggest that in the hypoxic heart a) ecto-5'-nucleotidase most likely is not involved in the formation of adenosine, b) release of adenosine from the heart requires adenosine to be transported across the sarcolemma membrane, and c) adenosine is predominantly formed intracellularly, a process involving cytosolic 5'-nucleotidase and/or S-adenosylhomocysteine hydrolase.
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PMID:Different sites of adenosine formation in the heart. 626 1

Cultures from various normal and neoplastic cell lines exfoliated vesicles with 5'-nucleotidase activity which reflected the ecto-enzyme activity of the parent monolayer culture. The ratio of 5'-nucleotidase to ATPase activity in the microvesicles indicated that cellular ecto-ATPase was conserved in the exfoliative process. Phospholipids of the microvesicles contained significantly increased amounts of sphingomyelin and total polyunsaturated fatty acids. It was concluded that the shedded vesicles constituted a select portion of the plasma membrane. Examination by electron microscopy showed the vesicles had an average diameter of 500 to 1000 nm and often contained a second population of vesicles about 40 nm in diameter. As much as 70% of the plasma membrane ecto-5'-nucleotidase activity of a culture was released into the medium over a 24-h period. Phosphoesterhydrolases from C-6 glioma or N-18 neuroblastoma microvesicles dephosphorylated cell surface constituents when in contact with monolayer cultures. Exfoliated membrane vesicles may serve a physiologic function; it is proposed that they be referred to as exosomes.
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PMID:Exfoliation of membrane ecto-enzymes in the form of micro-vesicles. 626 76

Adenosine synthesis was studied during 2-deoxyglucose-induced ATP catabolism in intact rat polymorphonuclear leucocytes. When both adenosine kinase (EC 2.7.1.20) and adenosine deaminase (EC 3.5.4.4) were selectively inhibited, adenosine accumulated. Adenosine formation took place inside the intact cells by a metabolic pathway independent of the ecto-5'-nucleotidase (EC 3.1.3.5). Distinct metabolic pathways are proposed for adenosine production from intracellular or extracellular nucleotides.
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PMID:Adenosine production inside rat polymorphonuclear leucocytes. 628 Jun 85


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