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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 specificity of lactoperoxidase-catalyzed iodination for the proteins of the hepatoma tissue culture cell plasma membrane was examined by histochemical, biochemical, and cell fractionation techniques. Light microscope autoradiography of sectioned cells shows the incorporated label to be localized primarily at the periphery of the cell. Most of this label can be released from the cell by trypsin but not by collagenase or hyaluronidase. The label is recovered from the cells as either monoiodotyrosine or diiodotyrosine after hydrolysis of cell extracts with a mixture of proteolytic enzymes. The label co-purifies during cell fractionation with an authentic liver cell plasma membrane marker enzyme, 5'-nucleotidase. Thus, the incorporated iodide is itself a valid marker for those membrane polypeptides having tyrosine residues accessible to the lactoperoxidase. The polypeptide complexity of the purified plasma membrane was examined by high resolution dodecyl sulfate-polyacrylamide gel electrophoresis. At least 50 polypeptides in the membrane are accessible to iodination. These polypeptides probably represent the bulk of the protein mass of the membrane and iodinating them does not affect cell viability, growth rate, or cell function. Labeling experiments with fucose and glucosamine show that at least nine of the iodinated peptides may be glycoproteins.
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PMID:Proteins of the hepatoma tissue culture cell plasma membrane. 0 57

Several histochemical tests were applied to the lining and glandular gastric epithelium of Xenodon merremii. Our observations, after discussion and interpretation, conducted to the following conclusions: 1. the surface epithelial cells, the neck cells, the body cells and the pyloric cells showed neutral polysaccharides, arginine, tyrosine, cysteine, acid phosphatase, AMPase and esterase. 2. besides these substances, in the surface epithelial cells was found tryptophan and in the body cells tryptophan and RNA.
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PMID:Polysaccharides, proteins, nucleic acids, enzymes and sulfate uptake of the gastric epithelial cells of Xenodon merremii Wagler, 1824 (Ophidia): an histochemical and autoradiographic study. 17 23

A histochemical and autoradiographic study of the lining intestinal epithelium of the snake Xenodon merremii is reported. The absorptive cells present neutral polysaccharides, arginine, tyrosine, tryptophan, cysteine, alkaline phosphatase, acid phosphatase, ATPase, AMPase, esterase and RNA. There are histochemical differences between the goblet cells of the small and of the large intestine. Whereas in the former predominates the neutral polysaccharides and are found arginine, tyrosine, tryptophan and cysteine, in the latter predominates the sulfated polysaccharides (confirmed by the uptake of radioactive sulfur) and no amino acids were found.
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PMID:Histochemical (polysaccharides, proteins, nucleic acids and enzymes) and autoradiographic (incorporation of 35S labelled sodium sulfate) study of the epithelial intestinal cells of Xenodon merremii Wagler, 1824 (Ophidia). 40 42

We have utilized S-farnesyl-Leu-Ala-Arg-Tyr-Lys-Cys as a methyl-accepting substrate to characterize a membrane-bound C-terminal protein methyltransferase from rat liver. We have localized the activity to the microsomal fraction and show that the bulk of the enzyme fractionates by density gradient centrifugation with glucose-6-phosphatase, a marker of the endoplasmic reticulum, and not with 5'-nucleotidase, a marker of the plasma membrane, or galactosyl:N-acetylglucosamine transferase, a marker of the Golgi apparatus. This methyltransferase appears to form an integral part of the membrane structure. Its activity is markedly affected by a variety of detergents used to solubilize membrane proteins in their native form. All activity is lost when membranes are treated with seven different detergents at a concentration of 1% (w/v). The activity is inhibited by N-ethylmaleimide, although it can be protected against inactivation with its substrate S-adenosyl-L-methionine, or its product S-adenosyl-L-homocysteine. Finally, we find that 5'-methylthioadenosine, a substrate analogue reported to be an inhibitor of this activity in other studies, is not an effective inhibitor in vitro.
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PMID:Characterization of a rat liver protein carboxyl methyltransferase involved in the maturation of proteins with the -CXXX C-terminal sequence motif. 132 16

A pleiotropic mutation (cpm) which is localised in the vicinity of the spoA gene of Bacillus subtilis chromosome has been described. The mutation inhibits spore formation, renders bacteria auxotrophic for adenine and tyrosine, increases sensitivity to antibiotics, decreases cell motility and the ability to grow on D-ribose and D-xylose, inhibits growth of bacteriophages PBS1 and AR9 as well as enhances activity of alkaline proteinase and alpha-amylase. At the same time, the cpm mutants acquire the ability to produce inosine. Inosine excretion is connected with more than 50- and 5-fold increase in activity of 5'-nucleotidase in respect to IMP and AMP, accordingly, and 10-fold decrease in activity of purine nucleoside phosphorylase. Biosynthesis of inosine and Ade- phenotype of the cpm mutant are not mediated by the change in activity of sAMP synthetase. The nature and mechanism of action of the cpm mutation are under discussion.
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PMID:[A new pleiotropic mutation affecting purine metabolism, sporulation and biosynthesis of exoenzymes in Bacillus subtilis]. 177 39

A pleiotropic mutation (cpm) which is localized in the vicinity of the spoOA gene is described in Bacillus subtilis. The mutation inhibits spore formation, rendering bacteria auxotrophic for adenine and tyrosine, enhances sensitivity to antibiotics, decreases cell motility, inhibits the ability to grow on pentoses and to maintain bacteriophage multiplication, induces severalfold the activities of alkaline proteinase and alpha-amylase. At the same time, the cpm mutant starts to excrete inosine into the growth medium. This excretion most probably is explained by a 50-fold increase in the activity of inosine monophosphate: 5'-nucleotidase and a 10-fold decrease in the activity of purine nucleoside phosphorylase. The inosine production and Ade- phenotype of the cpm mutant is not accompanied by the change in the activity of succinyl adenosine monophosphate synthetase. The nature of the mutation is discussed.
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PMID:A pleiotropic mutation affecting purine metabolism in Bacillus subtilis. 212 15

A cDNA was cloned coding for human placental 5'-nucleotidase. The 3547-bp cDNA contains an open reading frame that encodes a 574-residue polypeptide with calculated size of 63 375 Da. The NH2-terminal 26 residues comprise a signal peptide, which is followed by the NH2-terminal sequence of the purified protein. four potential N-linked glycosylation sites are found in the molecule, accounting for a larger mass of the mature form (71 kDa). The predicted structure contains a hydrophobic amino acid sequence at the COOH terminus, a possible signal for the post-translational modification by glycophospholipid. To confirm this possibility, we tried to isolate and characterize the membrane-anchoring domain of 5'-nucleotidase. BrCN-cleaved fragments of the protein were extracted with hexane and subjected to HPLC, resulting in purification of a single component of 2.3 kDa. Chemical analyses revealed that the purified fragment contains the tetradecapeptide Lys-Val-Ile-Tyr-Pro-Ala-Val-Glu-Gly-Arg-Ile-Lys-Phe-Ser, ethanolamine, glucosamine, mannose, inositol, palmitic acid, and stearic acid. The peptide sequence determined is identified at positions 510-523 in the primary structure deduced from the cDNA sequence, which predicts a further extension to position 548, containing the hydrophobic amino acid sequence. Thus, it is concluded that the mature 5'-nucleotidase lacks the predicted COOH-terminal peptide extension (524-548), which has been replaced by the glycophospholipid functioning as the membrane anchor of 5'-nucleotidase.
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PMID:Primary structure of human placental 5'-nucleotidase and identification of the glycolipid anchor in the mature form. 212 26

The involvement of glycosylphosphatidylinositol (GPI) in membrane anchoring of 5'-nucleotidase was investigated by chemical analyses. 5'-Nucleotidase purified from rat liver microsomes was subjected to BrCN cleavage, hexane extraction, and high-performance liquid chromatography, resulting in the purification of a single fragment with Mr 2300. Chemical analyses revealed that the purified fragment contains the tetradecapeptide Lys-Val-Ile-Tyr-Pro-Ala-Val-Glu-Gly-Arg-Ile-Lys-Phe-Ser and characteristic components of GPI including ethanolamine, glucosamine, mannose, inositol, palmitic acid, and stearic acid. In addition, it was confirmed that digestion of 5'-nucleotidase with lysyl endopeptidase yielded a fragment containing the dipeptide Phe-Ser and the same GPI components as above. The sequences of the tetradeca- and dipeptides thus determined are identified at positions 510-523 and 522-523, respectively, in the primary structure deduced from the cDNA sequence, which predicts a further extension to position 548, containing a hydrophobic amino acid sequence [Misumi, Y., Ogata, S., Hirose, S., & Ikehara, Y. (1990) J. Biol. Chem. 265, 2178-2183]. Taken together, these results indicate that the mature 5'-nucleotidase molecule lacks the predicted COOH-terminal peptide extension and is attached at serine-523 with GPI, which functions as the membrane anchor of 5'-nucleotidase.
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PMID:Membrane-anchoring domain of rat liver 5'-nucleotidase: identification of the COOH-terminal serine-523 covalently attached with a glycolipid. 214 14

Several newly synthesized 4-hydroxycinnamamide derivatives such as 3-(3',5'-di-isopropyl-4'-hydroxybenzylidene)-2-oxindol (ST 280), 3-(3',5'-di-methylthiomethyl-4'-hydroxybenzylidene)-2-oxindole (ST 458), alpha-cyano-3-ethoxy-4-hydroxy-5-phenylthiomethylcinnamamide (ST 638) and 3-(3'-ethoxy-4'-hydroxy-5'-phenylthiomethylbenzylidene)-2-pyrol idinone (ST 642) were found to inhibit tyrosine-specific protein kinase activity of the epidermal growth factor (EGF) receptor with IC50 values of 0.44 microM, 0.44 microM, 0.37 microM and 0.85 microM, respectively. None of them showed inhibitory effect on the enzyme activities of serine- and/or threonine-specific protein kinases such as cAMP-dependent protein kinase, Ca2+/phospholipid-dependent protein kinase C, casein kinase I and casein kinase II. In addition, none of them had effect on Na+/K+-ATPase or 5'-nucleotidase. The results suggest that the compound ST 280, ST 458, ST 638 and ST 642 are potent and specific inhibitors of tyrosine-specific protein kinase.
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PMID:Specific inhibitors of tyrosine-specific protein kinase, synthetic 4-hydroxycinnamamide derivatives. 282 Mar 97

ATPase activities in CNS membranes were studied after administration of desipramine (DMI), a noradrenaline (NA) uptake inhibitor. In a previous paper we reported that Na+,K(+)-ATPase activity significantly increased 3 h after DMI administration (10 mg/kg) in hypothalamus and mesencephalus but not in cerebral cortex and pons-medulla oblongata membranes (Viola et al., Cell. molec. Neurobiol. 1989, 9, 263-271). Here it was observed that Na+,K(+)-ATPase increase induced by acute DMI disappeared at 24 h in hypothalamus but remained during 21 days in mesencephalus. Na+,K(+)-ATPase increase by acute DMI was inhibited when endogenous NA was depleted by the noradrenergic neurotoxin DSP-4 or the NA synthesis inhibitor alpha-methyl-p-tyrosine. On the whole, Mg(2+)-ATPase activity was not modified by treatment. 5'-nucleotidase, another membrane-bound enzyme, was unchanged by acute DMI. The addition of DMI in vitro (50 ng/mg tissue) during Na+,K(+)-ATPase assay failed to affect ATPase activities. Acute DMI effects on Na+,K(+)-ATPase are thus attributable to noradrenergic neurotransmission rather than to non-specific drug-CNS membrane interaction. Furthermore, DMI produces differential effects on membrane Na+,K(+)-ATPase, depending on treatment conditions and CNS area studied.
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PMID:Na+,K(+)-ATPase activity in CNS and noradrenergic neurotransmission: time course of differential desipramine (DMI) effects. 813 Jul 40


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