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)

Fresh peripheral blood lymphocytes from eight patients with congenital agammaglobulinemia demonstrate reduced ecto-5'-nucleotidase activity when compared to the mean activity of normal subjects and patients with other forms of immunoglobulin deficiency. A specific defect of ecto-5'-nucleotidase is further suggested by normal values for lymphocyte ecto-adenosinetriphosphatase and ecto-nonspecific phosphatase. The data provide evidence for an enzyme deficiency in this X-linked, B lymphocyte deficiency syndrome.
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PMID:Lymphocyte ecto-5'-nucleotidase deficiency in agammaglobulinemia. 2 64

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

Because ecto-5'-nucleotidase activity of rat glomerular mesangial cells has been shown to increase upon interaction with macrophages in vitro, it was examined whether interleukin-1 beta (IL-1 beta) and tumour necrosis factor-alpha (TNF-alpha), two macrophage-released cytokines, were responsible for this effect. IL-1 beta and TNF-alpha stimulated mesangial cell 5'-nucleotidase activity in a dose-dependent manner after treatment for 24 hr. Maximum increases reached 4.5 times and 1.7 times basal values for IL-1 beta (20 U/ml) and TNF-alpha (25 ng/ml), respectively. The effects of both cytokines were additive. Stimulation of 5'-nucleotidase by IL-1 beta and TNF-alpha was specific since the activity of other ectoenzymes, such as Mg2(+)-ATPase, was unchanged. Cycloheximide, a blocker of protein synthesis, suppressed the cytokine-dependent increase of 5'-nucleotidase activity. Cyclo-oxygenase inhibitors such as indomethacin and ibuprofen inhibited approximately 50% of the effects of both cytokines. Their inhibitory effect was abolished in the presence of prostaglandin E2 (PGE2). In addition, PGE2 itself produced a dose-related (0.1-10 microM) increase of 5'-nucleotidase activity with a maximum of 2.2 times basal value. Taken together, these results indicate that IL-1 beta, essentially, and TNF-alpha, to a lesser extent, regulate 5'-nucleotidase expression in the plasma membrane of cultured mesangial cells and that their effect depends in part on PGE2 synthesis. Therefore, macrophages, via their products of secretion acting on 5'-nucleotidase, could modulate adenosine production in the glomerular capillaries.
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PMID:Induction of ecto-5'-nucleotidase of rat cultured mesangial cells by interleukin-1 beta and tumour necrosis factor-alpha. 216 99

Because rat peritoneal macrophages exhibit a particular binding capacity to rat glomerular mesangial cells in vitro, we have studied the effect of macrophages on two plasma membrane enzymes, ecto-5'-nucleotidase and ecto-Mg2+ ATPase, or rat cultured mesangial cells. A marked increase of ecto-5'-nucleotidase activity was observed in cocultures of rat mesangial cells and peritoneal macrophages. In addition, macrophage-conditioned medium (MCM) produced a dose-dependent increase of mesangial cell ecto-5'-nucleotidase activity. In contrast, ecto-Mg2+ ATPase activity was unaffected. The effect of MCM on ecto-5'-nucleotidase activity was apparent after 24 hours and increased with time. Reversion was obtained by MCM withdrawal. Stimulation of ecto-5'-nucleotidase activity by MCM was inhibited by cycloheximide, which suggests that protein synthesis was required. Induction of enzyme activity by MCM depended in part on the presence of extracellular adenosine. The macrophage-released factor responsible for this effect was non-dialysable, heat-stable at 56 degrees C for 30 minutes but heat-inactivated at 100 degrees C for five minutes, inactivated in the presence of trypsin or protease V8, and adsorbed on charcoal. Its apparent molecular weight estimated by gel chromatography was close to 20 kD. MCM from resident macrophages was as potent as MCM from thioglycollate-elicited or zymosan-stimulated macrophages. This stimulatory effect was specific of macrophages since it was absent in the culture medium of rat fibroblasts or mouse thymocytes but present in that of mouse macrophages. These results suggest that peritoneal macrophages synthesize a factor which selectively stimulates ecto-5'-nucleotidase activity of glomerular mesangial cells.
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PMID:Macrophages selectively stimulate ecto-5'-nucleotidase activity of cultured mesangial cells. 255 Jun 95

We have previously assigned human ecto-5'-nucleotidase (NT) to chromosome 6 on the basis of conversion of exogenously supplied [14C]AMP to adenosine by whole cells of human and Chinese hamster hybrids carrying chromosome 6. In this paper we demonstrate that the activity on human MRC-5 fibroblasts is typical of previously described and purified ecto-5'-nucleotidases. In contrast to MRC-5 cells, Chinese hamster V79A2 cells weakly express an AMPase activity that is not NT. The cytosolic form of NT in human and hybrid fibroblasts is similar to the ectoenzyme in substrate specificity. Hybrids that lack chromosome 6 express neither the ecto- nor the cytosolic enzyme, suggesting that both forms may be coded by the same gene on chromosome 6. Ecto-ATPase, ecto-ADPase, and ecto-ADP kinase activities are each expressed at similar levels in MRC-5 and V79A2. The ATPase, ADPase and NT activities of MRC-5 cells act sequentially to generate adenosine. A similar cascade acts on V79A2 cells but the lack of NT causes the accumulation of AMP.
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PMID:Nucleotide ectoenzyme activities of human and Chinese hamster fibroblasts in tissue culture. 256 Jun 29

We compared the properties of the ectonucleotidases (nucleoside triphosphatase, EC 3.6.1.15; nucleoside diphosphatase, EC 3.6.1.6; 5'-nucleotidase, EC 3.1.3.5) in intact pig aortic smooth-muscle cells in culture with the properties that we previously investigated for ectonucleotidases of aortic endothelial cells [Cusack, Pearson & Gordon (1983) Biochem. J. 214, 975-981]. In experiments with nucleotide phosphorothioate diastereoisomers, stereoselective catabolism of adenosine 5'-[beta-thio]triphosphate, but not of adenosine 5'-[alpha-thio]triphosphate, by the triphosphatase and stereoselective catabolism of adenosine 5'-[alpha-thio]diphosphate by the diphosphatase were found, as occurs in endothelial cells. In contrast with endothelial ecto-5'-nucleotidase, the smooth-muscle-cell enzyme catabolized adenosine 5'-monophosphorothioate (AMPS) to adenosine: the affinity of the enzyme for AMPS was greater than for AMP, and Vmax for AMPS was about one-sixth that for AMP. In both cell types AMPS was an apparently competitive inhibitor of AMP catabolism by 5'-nucleotidase. The relative rates of catabolism of nucleotide enantiomers in which the natural D-ribofuranosyl moiety is replaced by an L-ribofuranosyl moiety were similar to those in endothelial cells. No ectopyrophosphatase activity was detected in smooth-muscle cells, in contrast with endothelial cells, where modest activity is present.
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PMID:Characterization of ectonucleotidases on vascular smooth-muscle cells. 299 2

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

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

The components of the ectonucleotidase pathway at the immunoaffinity-purified striatal cholinergic synapse have been studied. The ecto-ATPase (EC 3.6.1.15) had a Km of 131 microM, whereas the ecto-ADPase (EC 3.6.1.6) had a Km of 58 microM, was Ca(2+)-dependent, and was inhibited by the ATP analogue 5'-adenylylimidodiphosphate (AMPPNP). The ecto-5'-nucleotidase (EC 3.1.3.5) had a Km of 21 microM, was inhibited by AMPPNP and alpha,beta-methylene ADP, and by a specific antiserum. The Vmax values of the ATPase, ADPase, and 5'-nucleotidase enzymes present at this synapse were in a ratio of 30:14:1. Very little ecto-adenylate kinase activity was detected on these purified synapses. The intraterminal 5'-nucleotidase enzyme, which amounted to 40% of the total 5'-nucleotidase activity, was inhibited by AMPPNP, alpha,beta-methylene ADP, and the antiserum, and also had the same kinetic properties as the ectoenzyme. The time course of ATP degradation to adenosine outside the nerve terminals showed a delay, followed by a period of sustained adenosine production. The delay in adenosine production was proportional to the initial ATP concentration, was a consequence of feedforward inhibition of the ADPase and 5'-nucleotidase, and was inversely proportional to the ecto-5'-nucleotidase activity. The function and characteristics of this pathway and the central role of 5'-nucleotidase in the regulation of extraterminal adenosine concentrations are discussed.
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PMID:Production of adenosine from extracellular ATP at the striatal cholinergic synapse. 841 43

The expression of P2 purinergic receptor subtypes in leukocytes varies with both lineage and developmental stage. Given the recent identification and cloning of at least seven distinct G protein-coupled ATP receptor subtypes (P2Y family), we investigated P2Y receptor subtype expression during myeloid cell differentiation. We observed that KG-1 myeloblasts express P2Y1 but not P2Y2 receptors (previously termed P2U receptors), whereas later myeloid progenitors, including HL-60 promyelocytes and THP-1 monocytes, expressed P2Y2 but not P2Y1 receptors. In KG-1 cells, significant activation of Ca2+ mobilization by P2Y1 receptors was only observed after preincubation with potato apyrase, an exogenous ATPase. This indicated that P2Y1 receptors are desensitized in KG-1 cells by autocrine mechanisms that may involve enhanced release of endogenous nucleotides and/or decreased expression of cell-surface ecto-nucleotidases. We compared the levels of ecto-apyrase activity and expression in KG-1 myeloblasts and HL-60 promyelocytes. Extracellular ATP was rapidly metabolized by HL-60 but not by KG-1 cells. Reverse transcription-polymerase chain reaction analysis indicated that mRNA for CD39 (cluster of differentiation), an identified ecto-apyrase, was present in HL-60 but not KG-1 cells. Ecto-apyrase activity was modestly increased with differentiation of myeloid progenitors with either phorbol 12-myristate 13-acetate (PMA) or dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP). Differentiation of HL-60 cells with PMA, but not DBcAMP, strongly induced ecto-5'-nucleotidase activity and CD73 mRNA expression. These observations indicate that signal transduction by extracellular ATP in myeloid leukocytes can be regulated by developmentally programmed changes in the expression of P2Y receptor subtypes and multiple ecto-nucleotidases.
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PMID:Stage-specific expression of P2Y receptors, ecto-apyrase, and ecto-5'-nucleotidase in myeloid leukocytes. 931 19


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