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)

The human hepatoma cell line (Li-7A) possesses a high concentration of epidermal growth factor (EGF) receptors and exhibits ectoATPase activity in the presence of either MgATP or CaATP (Knowles: J. Cell. Physiol., 134:109-116, 1988). Growth for 96 hours in the presence of both EGF and cholera toxin or another cyclic AMP elevating agent induced an ectoATPase activity which was more active with CaATP and resistant to inhibition by the sulfydryl reagent, p-chloromercuriphenylsulfonate (pCMPS) (Knowles: Arch. Biochem. Biophys., 263: 264-271, 1988). In contrast, treatment of cells with butyrate, a short chain organic acid which can be derived from the analogue, dibutyryl cyclic AMP, resulted in a 4-7-fold increase of an ectoATPase which was more active with MgATP and highly sensitive to pCMPS inhibition. Maximal induction by butyrate required 48 hours and was dependent on butyrate concentration, but was independent of EGF and cyclic AMP elevating agents. Of six organic acids tested, butyrate was most effective in the induction of the ectoMg2(+)-ATPase. The increase in the ectoMg2(+)-ATPase activity could be prevented with actinomycin D and cycloheximide, indicating that both transcription and translation were necessary for induction. In addition to the induction of the ectoMg2(+)-ATPase, butyrate induced alkaline phosphatase activity, but had no effect on a third ectoenzyme 5'-nucleotidase. These data further support our proposal that two distinct ectoATPases exist in the plasma membrane of Li-7A hepatoma cells.
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PMID:Butyrate induces an ectoMg2(+)-ATPase activity in Li-7A human hepatoma cells. 216 33

The human monocytic leukemia cell line, THP-1, is induced to differentiate into more functionally mature monocyte (macrophage)-like cells by incubation with retinoic acid at concentrations of 10nM or higher. There is no apparent morphological change accompanying this functional maturation. These induced cells show increases in nitroblue tetrazolium reduction, immunoerythrophagocytosis, hexose monophosphate shunt activity, and 5'-nucleotidase and NAD+-glycohydrolase activities. Prostaglandin E2, dibutyryl cyclic adenosine 3':5'-monophosphate, or T-lymphocyte-derived differentiation-inducing activity, all inactive or less active alone, increase the extent of differentiation of THP-1 in combination with 10nM retinoic acid. THP-1 is also induced to differentiate by 0.1nM or higher concentrations of cholera toxin. Furthermore, 24,24-difluoro-1 alpha,25-dihydroxyvitamin D3 induces less differentiation of THP-1 compared to retinoic acid. Dimethyl sulfoxide and 12-O-tetradecanoylphorbol-13-acetate show no induction of functional differentiation. THP-1 thus joins the list of leukemic myelomonocytic cell lines (e.g., the promyelocytic HL-60 and the monoblast-like U-937) that are blocked at a relatively late stage of maturation and which differentiate in response to retinoic acid.
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PMID:Induction of functional differentiation of a human monocytic leukemia cell line (THP-1) by retinoic acid and cholera toxin. 298 63

Subcellular fractionation techniques have been used to assess the localization of injected 125I-labeled cholera toxin (125I-CT) taken up by rat liver in vivo, and to determine whether internalization of the toxin is required for the generation of the active A1 peptide. The uptake of injected 125I-CT into the liver is maximal at 5 min (about 10% injected dose/g). At this time the radioactivity is for the most part recovered in the microsomal (P) fraction, but later on it progressively associates with the mitochondrial-lysosomal (ML) and supernatant fractions. The radioactivity is enriched 7-fold in plasma membranes at 5-15 min, and 15-60-fold in Golgi-endosome (GE) fractions at 15-60 min. On analytical sucrose gradients the radioactivity associated with the P fraction is progressively displaced from the region of 5'-nucleotidase (a plasma membrane marker) to that of galactosyltransferase (a Golgi marker). On Percoll gradients, however, it is displaced towards acid phosphatase (a lysosomal marker). Density-shift experiments, using Triton WR 1339, suggest that some radioactivity associated with the P fraction (at 30 min) and all the radioactivity present in the ML fraction (at 2 h) is intrinsic to acid-phosphatase-containing structures, presumably lysosomes. Comparable experiments using 3,3'-diaminobenzidine cytochemistry indicate that the radioactivity present in GE fractions is separable from galactosyltransferase, and thus is presumably associated with endosomes. The fate of injected 125I-labeled cholera toxin B subunit differs from that of the whole toxin by a more rapid uptake (and/or clearance) of the ligand into subcellular fractions, and a greater accumulation of ligand in the ML fraction. Analysis of GE fractions by SDS/polyacrylamide gel electrophoresis shows that, up to 10 min after injection of 125I-CT, about 80% of the radioactivity is recovered as A subunit and 20% as B subunit, similarly to control toxin. Later on there is a time-dependent decrease in the amount of A subunit and, at least with the intermediate GE fraction, a concomitant appearance of A1 peptide (about 15% of the total at 60 min). In contrast the radioactivity associated with plasma membranes remains indistinguishable from unused toxin. It is concluded that, upon interaction with hepatocytes, 125I-CT (both subunits A and B) sequentially associates with plasma membranes, endosomes and lysosomes, and that endosomes may represent the major subcellular site at which the A1 peptide is generated.
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PMID:Fate of injected 125I-labeled cholera toxin taken up by rat liver in vivo. Generation of the active A1 peptide in the endosomal compartment. 381 13

Highly purified plasma membranes of bovine thyroid were obtained by differential pelleting followed by discontinuous gradient centrifugation in a swing-out rotor. Subfractions of plasma membranes were prepared by affinity chromatography on Con A-Sepharose. The final membrane fractions were enriched 25-30-fold over homogenate in 5'-nucleotidase and alkaline phosphatase and displayed a protein to phospholipid ratio of 1.67 and a cholesterol to phospholipid molar ratio of 0.55. The phospholipid composition did not deviate appreciably from that of whole tissue except for the higher sphingomyelin level (22.5 vs. 14.0%). The predominant fatty acids were palmitic (16:0), oleic (18:1), stearic (18:0) and linoleic (18:2) acid. The physical state of the membrane was studied by (i) calculation of the lipid structural order parameter SDPH from steady-state fluorescence anisotropy determinations of the hydrophobic probe 1,6-diphenyl-1,3,5-hexatriene (DPH); (ii) estimation of the lateral diffusion coefficient of pyrene following excimer formation. These parameters were determined in native thyroid plasma membranes and in reconstituted vesicles, obtained by detergent dialysis from octylglucoside solubilized membrane components. The presence of membrane protein or neutral lipids induced more restraint on the movements of the fluorophores. The lipid order parameter, SDPH was mainly determined by the neutral lipids. Subfractions of plasma membrane enriched in luminal membranes have a slightly lower fluidity (higher SDPH and lower Ddiff values) than subfractions enriched in basolateral membranes. This difference appears to be due to both differences in lipid as well as protein composition. Under physiological conditions, no significant alterations in probe dynamics could be observed upon addition of thyrotropin or cholera toxin, even at micromolar concentrations.
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PMID:Fluidity characteristics of bovine thyroid plasma membranes. 397

Brush borders and plasma membranes have been purified from mucosal epithelial cells of rabbit ileum under control conditions and after treatment for 3 hr with cholera toxin in vivo. The activity of several enzymes in these preparations was measured. It was concluded that adenyl cyclase, like NaK-ATPase, seems not to be a normal constituent of brush borders. Both these enzymes are present in plasma membrane preparations derived largely from the basal and lateral margins of the epithelial cells, both may be phospholipid dependent enzymes and both are affected by cholera toxin. Adenyl cyclase activity is increased while NaK-ATPase is decreased. The activities of alkaline phosphatase, leucineaminopeptidase, 5'-nucleotidase, glucose-6-phosphatase, and Mg-ATPase were not found to be affected by the toxin. Cholera toxin, which makes contact with the luminal side of the epithelial cells, in the natural disease and in the experimental model, would appear to exert its pathologic effect on adenyl cyclase at the opposite (basal and lateral) side of the cells.
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PMID:Localization of the action of cholera toxin on adenyl cyclase in mucosal epithelial cells of rabbit intestine. 434 29

When intact guinea-pig granulocytes (polymorphonuclear leucocytes) disrupted by sonication or with detergent were treated with neuraminidase from Vibrio cholerae, 3.1--3.2 nmol of sialic acid/10(7) cells was released. By using a chromatographic procedure for the specific determination of total cell sialic acid, this releasable portion was found to constitute 70% of the total sialate. All of the neuraminidase-releasable sialic acid of the cells could be removed by enzymic treatment of intact cells with neuraminidase. It thus seemed likely that the neuraminidase-releasable sialic acid is all on the cell surface. To make sure that the result was not due to entry of neuraminidase into the cells, the enzyme was bound covalently to Sepharose 6B, and intact polymorphonuclear leucocytes were treated with the bound enzyme. All of the neuraminidase-releasable sialic acid could still be removed, though more slowly. The cells remained intact and only 1.5--2% of the bound enzyme was released from the Sepharose during incubation. Freed enzyme could have been responsible, at the very most, for release of 18% of the sialic acid. Fractionation studies showed that the nucleus and cytoplasm contain low amounts of sialic acid and that the neuraminidase-releasable sialic acid distributes in a manner similar to the distribution of 5'-nucleotidase, an unambiguous marker for the plasma membrane in these cells. Thus neuraminidase-releasable sialate constitutes a clear marker for the membrane of polymorphonuclear leucocytes. Most of the neuraminidase-insensitive sialate was present in the granule fraction. Removal of sialic acid from intact polymorphonuclear leucocytes did not affect their ecto-AMPase, -ATPase and -p-nitrophenyl phosphatase activities.
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PMID:The determination and localization of sialic acid in guinea-pig granulocytes. 626 58

In rabbit liver plasma membranes (LPM), specific binding of 125I-insulin rapidly increased in late gestation and peaked at birth, declining thereafter. In contrast, 125I-glucagon binding was lowest in late gestation, somewhat higher at birth, and increased by 48 h although only to 20-25% of adult. These changes in binding were due to changing numbers of receptors involving predominantly high affinity sites for insulin and low affinity sites for glucagon, with only minor changes in affinity. Despite measurable glucagon receptors by birth, fetal LPM produced no increment above basal in cAMP production with maximal doses of glucagon (10(-6) M), prostaglandin E1 (10(-4) M), or epinephrine (10(-4) M). Near birth only NaF (10 mM) produced a modest but significant increment in cAMP. By 2 h postbirth, all stimuli evoked significant increments in cAMP production that increased progressively but was still only 15-20% of adult at 48 h. Furthermore, although specific binding of cholera toxin was greater in fetal LPM (11 +/- 1 vs. 6 +/- 1%), cholera toxin-stimulated cAMP production increased by only 12-26% above basal in the fetus compared with 220% in adult. Markers of membrane purity including 5'-nucleotidase, phosphodiesterase, and insulin or glucagon degradation were not different in fetus and adult. We conclude that receptors and components of the adenylate cyclase complex mature independently; initial coupling occurs between the G/F regulatory protein and the catalytic unit (NaF but not hormonal activation) followed within hours of birth by coupling to the hormone receptor.
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PMID:Ontogeny of hepatic insulin and glucagon receptors and adenylate cyclase in rabbit. 630 5