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:3.1.3.5 (5'-nucleotidase)
3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An ATPase stimulated by HCO - ions 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 - 3 ions. No such ATPase was found in the rabbit duct, which normally does not secrete HCO - 3. The HCO - 3 ATPase was localized in the plasma membrane fraction of the homogenate, as evidenced by the marker 5'-nucleotidase. The activities of the HCO - 3 ATPase increased in metabolic alkalosis and decreased in metabolic acidosis in parallel to secretion of HCO - 3 and K+ ions by the duct epithelium. These findings provide further evidence that the membrane-bound HCO - 3 ATPase is involved in active H+/HCO - 3 transport.
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PMID:H+ transport and membrane-bound HCO - 3 ATPase in salivary duct epithelium. 0 8

Membrane vesicles can be prepared from murine lymphoid cells by nitrogen cavitation and fractionated by sedimentation through nonlinear sucrose density gradients. Two subpopulations of membrane vesicles, PMI and PMII, can be distinguished on the basis of sedimentation rate. The subcellular distribution of adenylate and guanylate cyclases in these membrane subpopulations have been compared with the distribution of a number of marker enzymes. Approximately 20-30% of the total adenylate and guanylate cyclase activity is located at the top of the sucrose gradient (soluble enzyme), the remainder of the activity being distributed in the PMI and PMII fractions (membrane-bound enzyme). More than 90% of the 5'-nucleotidase and NADH oxidase activities detected in lymphoid cell homogenates are located in PMI and PMII fractions, whereas succinate cytochrome c reductase activity is detected only in the PMII fractions. In addition, beta-galactosidase activity is distributed in the soluble and PMII fractions of the sucrose density gradients. On the basis of the fractionation patterns of these various enzyme activities, it appears that PMI fractions contain vesicles of plasma membrane and endoplasmic reticulum, whereas PMII fractions contain mitochondria, lysomes, and plasma membrane vesicles. Approximately 30-40% of the adenylate and guanylate cyclase activities in PMII can be converted to a PMI-like form following dialysis and resedimentation through a second nonlinear sucrose gradient. Adenylate and guanulate cyclases can be distinguished on the basis of sensitivity to nonionic detergents.
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PMID:The subcellular distribution of adenylate and guanylate cyclases in murine lymphoid cells. 0 90

Human skin fibroblasts, grown to confluency in the presence of 32P for random labelling of the phospholipids, showed upon 24 h incubation in the presence of either 8 mM L-serine or 4 mM ethanolamine an increased content of phosphatidylserine (150% of control cells) or phosphatidylethanolamine (116% of control cells), respectively. Concomitantly the phosphatidylcholine correspondingly decreased. Upon cell harvesting and gentle enzyme preparation the base-treated cells demonstrated a significantly higher unstimulated, fluoride- and thyrotropin-stimulated activity of adenylate cyclase. The activities of total ATPase, ouabain-sensitive ATPase, 5'-nucleotidase and gamma-glutamyltransferase remained unaltered. When subjecting enzyme preparations from fibroblasts to ultrasonication the activity of adenylate cyclase decreased progressively with energy applied, whereas the activities of the other enzymes were unaltered ((K+ + Na+)-ATPase, 5'-nucleotidase) or even increased (Mg2+-ATPase, gamma-glutamyltransferase). The results have a bearing upon the regulatory function of the phospholipid microenvironment of membrane-bound enzymes.
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PMID:The influence of changes in the phospholipid pattern of intact fibroblasts on the activities of four membrane-bound enzymes. 1 85

5'-Nucleotidase is purified from lymphocyte plasma membranes by two affinity chromatographies. The first one, on Lens culinaris lectin-Sepharose 4B yields a fraction of twelve lectin-binding glycoproteins (lectin-receptor fraction). The second one on 5'-AMP-Sepharose 4B leads to pure enzyme. This enzyme is a glycoprotein with a molecular weight of 130 000; it gives a single band in polyacrylamide/dodecylsulfate electrophoresis and displays a very high specific activity (2500-3000 mumol Pih-1mg-1). Some properties of purified 5'-nucleotidase are similar to those of membrane-bound enzyme: substrate specificity, temperature dependence, effects of ions and SH-blocking reagents. Others are completely different for the two systems and these differences result from an interaction between the enzyme molecule and other Lens culinaris lectin binding proteins.
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PMID:Purification and properties of 5'-nucleotidase from lymphocyte plasma membranes. 2 25

Immunological and biochemical studies of spontaneously metastasizing and nonmetastasizing rat mammary carcinomas and their plasma membranes indicated that: (i) all spontaneously metastasizing tumors have little or no demonstrable glycocalyx, while all nonmetastasizing tumors have a thick glycocalyx; (ii) there is a direct relationship between the glycocalyx and immunogenicity, and an inverse relationship with the metastasizing capacity of tumor cells, properties which can be quantitated by levels of the plasma membrane marker enzyme 5'-nucleotidase (EC3.1.3.5;5'-ribonucleotide phosphohydrolase) activity; (iii) the absence of glycocalyx from the metastasizing tumor cell surface seems to result from its dissociation from plasma membranes, for solubilized cell surface antigen is readily found in the blood of metastasizing tumor bearing rats, while there was no detectable tumor cell surface antigen in the blood of the nonmetastasizing tumor hosts tested; (iv) both metastasizing and nonmetastasizing mammary tumors appear to have a common soluble cell surface antigen; (v) in addition to this common antigen, there is another membrane-bound antigen in the nonmetastasizing, immunogenic tumor cell surface which presumably is the tumor specific transplantation antigen; and (vi) this antigen is immunobiologically unique, but seems to be immunochemically related to the common soluble antigen. It is postulated that the lack of an immunogenic coat and/or the presence of solubilized tumor cell surface antigen in the blood may provide an immune escape mechanism for tumor cells by interfering with cell-mediated immune response of tumor hosts, leading to their dissemination.
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PMID:Immunological escape mechanism in spontaneously metastasizing mammary tumors. 4 47

Plasma membranes from normal, full-term human placental trophoblast have been isolated by a new procedure. The method depends upon isopycnic zonal centrifugation using linear sucrose/Ficoll density gradients. Enrichment of plasma membrane marker enzymes with respect to trophoblast homogenate is found in two distinct peaks (designated B and D) of the fractionated effluent recovered from the rotor. Fraction B is enriched with membrane-bound alkaline phosphatase and 5'-nucleotidase, but not with (Na+, K+)-ATPase of F(-)-stimulated adenylate cyclase. It is suggested that this material is derived from the maternal-facing microvillous plasma membrane. Fraction D, enriched with (Na+, K+)-ATPase, F(-)-stimulated adenylate cyclase and, to a smaller extent, with 5'-nucleotidase and alkaline phosphatase is, by exclusion, proposed to be derived from the fetal-facing basal plasma membrane. Both plasma membrane fractions are shown to be free of appreciable contamination, using specific markers for endoplasmic reticulum, mitochondria, nuclei and lysosomes. The separation of the two membrane fractions is shown to depend both upon these membranes forming closed vesicles during homogenization and upon the buoyant densities of such vesicles differing in such a way that microvillous plasma membranes band at a lower density than basal plasma membranes. No separation of the membranes is achieved in gradients in which the vesicles are collapsed.
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PMID:Separation of the microvillous (maternal) from the basal (fetal) plasma membrane of human term placenta: methods and physiological significance of marker enzyme distribution. 9 48

The regulation of adrenergic receptors in rat heart was measured in rats made hyperthyroid by injection with thyroxine and made hypothyroid by addition of propylthiouracil to the drinking water. Hyperthyroid rats display cardiac hypertrophy and a decrease in epididymal fat pad weight. The maximal beta-receptor level of ventricular membranes, as determined by (-)-[3H]dihydroalprenolol binding, was increased 60% by thyroxine treatment and decreased about 30% by propylthiouracil treatment. The affinity of the beta receptor was unchanged after thyroxine or propylthiouracil treatment. The maximal activity of the isoproterenol-stimulated adenylate cyclase (EC 4.6.1.1) varied with thyroid state in a manner parallel to the increase in beta-adrenergic binding sites. Thyroxine treatment also increases by 2-fold the beta receptors in isolated rat fat cells. Propylthiouracil treatment lowered the level of alpha receptors in heart by 30% as measured by [3H]dihydroergocryptine binding, but increased the affinity about 2.5-fold. The highest level of alpha receptors was seen in control hearts. These studies indicate that thyroxine may control the turnover of beta-adrenergic receptors in heart and fat cells and regulate physiological responses in these tissues via a hormone-hormone interplay system. Thyroxine treatment reduced the activity of the membrane-bound Mg2+-ATPase (EC 3.6.1.3) and 5'-mononucleotidase (EC 3.1.3.5) but appears to increase the activity of the (Na+ + K+)ATPase (EC 3.6.1.4).
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PMID:Hormone action at the membrane level. VIII. Adrenergic receptors in rat heart and adipocytes and their modulation by thyroxine. 14 63

The preparation of right side-out vesicles from mouse plasmocytoma plasma membranes can be used to study the early functionnal events of the plasma membrane upon binding of ligands. Activation of two membrane-bound enzymes, 5'-nucleotidase and Na+/K+ ATPase, induced specifically by several anti-H-2 antisera was investigated. A simultaneous stimulation of these two enzymes was reported at high dilutions of antisera directed against antigens of the MHC. Comparison between the enzyme activation test and the classical cytotoxicity test showed the former being more sensitive than the latter by at least one order of magnitude. A structural coordination between some histocompatibility antigens and/or other cell surface receptors and the membrane-bound enzymes could be envisionned for the initiation of lymphocyte activation.
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PMID:Modulation of membrane-bound enzyme activity by binding of antibodies to major histocompatibility complex antigens. 15 18

The objective of this investigation was to find out whether vitamin E deficiency, apart from influencing the lipid component of cellular membranes, also influences the protein component. For that purpose a number of membrane-bound enzymes in the liver of the Pekin duckling were histochemically, cytochemically, and biochemically examined. Furthermore, cells, cellular membranes, and protein particles in membranes were morphometrically investigated. Histochemically five membrane-bound enzymes appeared to be stimulated in vitamin E deficiency: 5'-nucleotidase, glucose-6-phosphatase, isocitrate dehydrogenase (NADP), tetrazolium reductase (NADH), and tetrazolium reductase (NADPH). 5'-Nucleotidase and glucose-6-phosphatase were also investigated cytochemically and biochemically. The cytochemical localization of these enzymes was identical in control and vitamin E-deficient ducklings. Biochemically, a stimulation of these two enzymes also could be demonstrated. The increase per milligram of DNA appeared to be largest whereas the increase per milligram of protein, per milligram of phospholipid, and per milligram of RNA was only half of the increase per milligram of DNA. This can be explained by the 30 per cent increase of the cell volume in vitamin E deficiency leading to an increase of protein, phospholipid, and RNA per cell. The thickness of membranes and the diameter of protein particles in membranes were measured in liver parenchymal cells. In vitamin E deficiency the thickness of the outer mitochondrial membrane and the diameter of protein particles in this membrane were smaller whereas the thickness of the endoplasmic reticular membrane was larger. The increase of the activities of mitochondrial and microsomal enzymes and the decrease of the thickness of the outer mitochondrial membrane and of its protein particles are interpreted to be the result of the influence of free radicals on membranes with electron transport functions. The increase of 5'-nucleotidase activity in the plasma membrane is likely to have a different cause; it may be related to the transport of nucleotides across this membrane.
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PMID:Cellular membranes and membrane-bound enzymes in vitamin E deficiency. A histochemical, cytochemical, biochemical, and morphologic study of the liver of the Pekin duckling. 16 37

As it was shown previoulsy by others, the membrane-bound phosphodiesterase (cyclic adenosine 3':5'-monophosphate phosphodiesterase) of rat epididymal fat cells was stimulated when intact cells were exposed to insulin. The levels of stimulation observed in the present study in the cell homogenate and microsomal fraction were approximately 2.0- to 2.5-fold and 2.5- to 3.0-fold, respectively, when the initial substrate level was 100 nM and insulin concentration was 1 to 3 nM. When the microsomal fraction was subjected to a sucrose density gradient centrifugation, most of the insulin-sensitive phosphodiesterase activity was fractionated into the "light" microsomal fraction which was rich in NADH2:potassium ferricyanide:oxidoreductase) and low in 5'-AMPase, adenylate cyclase, and insulin-binding activities. The latter three activities were mostly fractionated into the "heavy" microsomal fraction. Both basal and insulin-stimulated phosphodiesterase activities were low when cells were homogenized in the presence of N-ethylmaleimide or p-chloromercuribenzoate. The insulin-stimulated enzyme activity was also low when cells were homogenized in the presence of --SH compounds (e.g. dithiothreitol) or certain metal-chelating agents (e.g. ethylene glycol bis(beta-aminoethyl ehter)-N,N'-tetraacetate (EGTA)), or in a nitrogen atmosphere. The effect of EGTA was prevented by the addition of certain heavy metal ions but not by the addition of Ca2+ or Ca2+ plus Mg2+ ions. When cells were homogenized in the presence of certain oxidants (e.g. diamide, sodium tetrathionate, or air), a high plus-insulin activity was observed; this activity was not lowered by subsequent treatment of the enzyme with N-ethylmaleimede, EGTA, or fresh cell homogenate that was prepared in the presence of EGTA. However, the activity of an apparently oxidized enzyme could still be lowered by treatment woth dithiothreitol. A partially purified enzyme in the enzyme in the microsomal fraction was fairly stable both in basal and insulin-stimulated states (fully active after 35 days when kept at -20degrees). EGTA added to the homogenization buffer lowered the basal phosphodiesterase activity, but this effect was reversed by the addition of Ca2+ ions. EGTA also decreased the enzyme activity that was stimulated by norepinephrine. However, neither EGTA nor dithiothreitol had any effect on the activities of 5'-AMPase, NADH-dehydrogenase, and malate dehydrogenase of fat cells. The above data indicate that most of the insulin-sensitive phosphodiesterase and the so-called "cell membrane markers" are associated with different subcellular particles in the cell homogenate. In addition, the data seem to indicate that the insulin-stimulated phosphodiesterase has certain --SH groups and that the activity of the enzyme is stabilized when the --SH groups are oxidized by certain oxidants including molecular oxygen. It is suggested that the air oxidation of the enzyme is catalyzed by a trace of certain heavy metal ions and, therefore, can be blocked by a metal-chelating agent.
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PMID:Insulin-sensitive phosphodiesterase. Its localization, hormonal stimulation, and oxidative stabilization. 17 Feb 71


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