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)

Three lysosomal glycosidases, beta-glucuronidase (EC 3.2.1.31), beta-galactosidase (EC 3.2.1.23), and N-acetyl-beta-glucosaminidase (EC 3.2.1.30) have been investigated in bile that was freshly collected from rats through a complete bile fistula. Assay conditions have been established on the basis of appropriate kinetic studies. The biliary excretion patterns for these enzymes were found to vary considerably from rat to rat during the 24-h collection period. In a given animal, however, the three hydrolases were excreted in parallel and showed a gradual increase in activity with time, most marked after 10- 12 h of collection. 24-h biliary outputs of the three hydrolases averaged congruent with3% of their respective contents in total liver, and bile diversion had no effect on hepatic glycosidase activity or total protein content. Other enzymes known to be associated primarily with mitochondria, endoplasmic reticulum, and cell sap were also detected in bile, generally in smaller amounts. The biliary excretion of the plasma membrane markers, alkaline phosphodiesterase I and 5'-nucleotidase, however, was comparable to that of the lysosomal hydrolases. Biliary excretion of total protein was relatively constant and corresponded to 3.0% of the total hepatic protein content per day, whereas biliary bile acid secretion decreased during the first 12 h and then remained constant. Exocytic bulk discharge of hepatocyte lysosomes is proposed as the most likely mechanism for the biliary excretion of lysosomal enzymes. These results call attention to the possible pathophysiologic significance of biliary excretion of hepatic lysosomal contents as a means of residue disposal.
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PMID:Coordinate secretion of acid hydrolases in rat bile. 11 27

The activities of subcellular marker enzymes in bile and liver homogenate from several mammalian species have provided information on the specificity of protein release during bile formation. The presence of significant amounts of the plasma membrane enzymes alkaline phosphodiesterase I and leucyl-beta-naphthylamidase in bile, in addition to alkaline phosphatase and 5'-nucleotidase, and the relative absence of intracellular enzymes lends support to the view that bile salt liberation from the hepatocyte is accompanied by a partial solubilization of the plasma (canalicular) membrane without extensive damage to the whole hepatocyte.
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PMID:Enzyme profiles of mammalian bile. 16 72

Glycocholate and taurocholate removed from isolated pig lymphocytes a proportion of the cells' complement of 5'-nucleotidase, alkaline phosphatase and alkaline phosphodiesterase I before cell lysis. This may indicate a loss of externally orientated plasma-membrane components.
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PMID:Plasma-membrane components can be removed from isolated lymphocytes by the bile salts glycocholate and taurocholate without cell lysis. 18 40

In populations of cultured arterial endothelial and smooth muscle cells grown under the same conditions, we have measured the total activity per cell of 10 enzymes commonly used as "markers" for subcellular organelles: NADH: ferricyanide reductase, NADH:cytochrome c reductase (rotenone insensitive). NADPH:cytochrome c reductase, alpha-glucosidase, 5'-nucleotidase, alkaline phosphodiesterase I, cytochrome oxidase, monoamine oxidase, cathepsin D, and N-acetyl-beta-glucosaminidase. Significant differences between the cell types were found for 7 of the 10 enzymes tested. The total activity of 5'-nucleotidase in cultured smooth muscle cells was 17 times that of cultured endothelial cells. Comparison of the activities in the two cell types freshly collected and in culture showed that the difference in 5'-nucleotidase in cultured cells is due principally to loss of activity from endothelial cells, suggesting that this activity is regulated differently in the two cell types. In both cell types cathepsin D activity rose during culture.
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PMID:Enzyme activities in endothelial cells and smooth muscle cells from swine aorta. 22 46

Homogenates of HTC cells have been fractionated by differential centrifugation (in four particulate fractions: N, M, L, P, and a supernatant S) or isopycnic banding in linear sucrose gradients. On this basis, the following subcellular organelles may be characterized: (i) Mitochondria, detected by cytochrome oxidase and succinodehydrogenase, are collected in the M and L fractions, and equilibrate, as a narrow band, at a median buoyant density of 1.18 g/cm3. (ii) Lysosomes, detected by the latent hydrolases beta-glycerophosphatase and N-acetyl-beta-glucosaminidase, are largely sedimented in the M and L fractions, and display a broad density distribution pattern with a median value of 1.17 g/cm3. This density is decreased or increased after cultivation of the cells in presence of Triton WR-1339 or Dextran 500, respectively. The behavior of cathepsin D is somewhat at variance with that of the two other hydrolases. (iii) Plasma membrane is tentatively detected by alkaline phosphodiesterase I. Largely recovered in the P fraction, this enzyme equilibrates at a median density close to that of the lysosomal hydrolases; the bulk of cholesterol and about half of the leucyl-2-naphthylamidase are closely associated with alkaline phosphodiesterase I; HTC cells do not contain typical 5'-nucleotidase. (iv) Catalase-bearing particles, of high buoyant density (1.22 g/cm3) are present, but 30-40% of the catalase is also found readily soluble. NADPH- and NADH: cytochrome c reductase, and RNA show more complex distributions. It is suggested that the former enzyme is associated with the endoplasmic reticulum; as in liver, NADH reductase activity is shared between the endoplasmic reticulum and the mitochondria; half of the RNA is associated with free ribosomes of polysomes. True glucose-6-phosphatase could not be detected.
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PMID:Analytical fractionation of cultured hepatoma cells (HTC cells). 56 43

Homogenization of guinea pig liver in isotonic sucrose solution followed by the separation of the subcellular fractions by differential centrifugation releases the liver L-asparaginase (L-asparagine amidohydrolase, EC 3.5.1.1) activity into the supernatant fraction. Electron micrographs of the liver L-asparaginase-antibody complexes, precipitated from the clear supernatant phase by addition of L-asparaginase-specific antiserum, show membrane-liek structures and some amorphous material. The attachment of L-asparaginase to the membrane-like structures is indicated by the ferritin-labeled antibody technique. The immunoprecipitates possess low activities of 5'-nucleotidase, alkaline phosphodiesterase I, NADPH cytochrome c reductase, glucose-6-phosphatase, and acid phosphatase. This observation suggests that L-asparaginase found in the liver supernatant fraction is associated with cytomembrane components. Analysis of guinae pig serum L-asparaginase-antibody complexes is polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate gives three distinct protein bands. These bands correspond to heavy and light chains of rabbit immunoglobulins and the L-asparaginase subunits. Analysis of the liver L-asparaginase-antibody complexes by the above procedure shows similar but more diffuse protein bands.
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PMID:Evidence for the association of L-asparaginase with cytomembrane components in the guinea pig liver soluble fraction. 81 93

A number of organic anions are known to decrease biliary secretion of cholesterol and phospholipid without affecting bile acid secretion. Cyclobutyrol (CB) is a choleretic agent which also inhibits biliary lipid secretion. Using isolated perfused rat liver we have studied this inhibition in relation to possible mechanisms suggested for other anions. Shortly after its administration to the isolated perfused liver, CB decreases biliary outputs of cholesterol and phospholipid, without changes in bile acid secretion, at low (450 nmol/min), high (1350 nmol/min) and nil taurocholate infusion rates. The absolute inhibition does not appear to be decreased by elevated bile acid secretion. There is a differential effect on secretion of cholesterol and phospholipid, more marked at low bile acid secretion rates. Biliary outputs of the canalicular membrane enzymes 5'-nucleotidase and alkaline phosphodiesterase I are also depressed by CB administration, but the anion does not affect the biliary output of bovine serum albumin or the output of rat serum albumin into the perfusion fluid. Since CB does not inhibit intracellular vesicular transport or apparently inhibit intracanalicular events, its effect is different from the effect of several other anions. From these studies it appears that the most likely effect of CB is exerted at the level of the canalicular membrane.
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PMID:Inhibitory action of cyclobutyrol on the secretion of biliary cholesterol and phospholipids. 231 Mar 70

We have undertaken the analytical fractionation of epithelial cells from toad urinary bladder, a tissue extensively used to study epithelial transport of ions and water. In an attempt to establish markers for the main subcellular organelles, a number of enzymes were assayed in cell homogenates. The nearly ubiquitous plasma membrane marker 5'-nucleotidase, and the transferases that donate N-acetylglucosaminyl, galactosyl, and sialyl residues to glycoproteins and glycolipids in the Golgi complex were not detectable. Glucose-6-phosphatase activity was low in relation to that of nonspecific phosphatases and, therefore, not suitable for identifying the endoplasmic reticulum. Like the cytosolic enzyme lactate, dehydrogenase, catalase was essentially found in the high-speed supernatant, with a noteworthy part of aminopeptidase (substrate, leucyl-beta-naphthylamide) and NAD glycohydrolase. Other enzymes, including cytochrome c oxidase, acid phosphatase, acid N-acetyl-beta-glucosaminidase, alkaline phosphatase, alkaline phosphodiesterase I, nucleoside diphosphatase (substrate ADP), oligomycin-resistant Mg++-ATPase, and mannosyltransferase (acceptor, dolichylphosphate) were fairly active and largely sedimentable. After differential centrifugation, cytochrome oxidase, acid phosphatase, and acid N-acetyl-beta-glucosaminidase were typically associated with the large granule fraction, whereas the other sedimentable enzymes exhibited a broad distribution profile overlapping the nuclear, large granule, and microsome fractions. Their behavior in density equilibrium centrifugation is examined in a companion paper.
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PMID:Subcellular fractionation of epithelial cells from toad urinary bladder. 1. Assay of marker enzymes and differential centrifugation. 250 71

In order to label the vesicles involved in transcellular transfer (transcytosis) through hepatocytes, polymeric IgA (pIgA) was conjugated to horseradish peroxidase (HRP) and injected into rats. The endosomes containing this ligand at 10 or 20 min after injection were isolated by the diaminobenzidine-induced density-shift procedure and their content in various marker enzymes was measured. The endosomes carrying pIgA-HRP 10 min after injection contained only traces of 5'-nucleotidase and low amounts of alkaline phosphodiesterase I. The estimated marker enzyme content is similar to that observed for the particles containing galactosylated bovine serum albumin conjugated to HRP, a ligand degraded in lysosomes. However, 20 min after injection, the transcytotic endosomes showed a marked enrichment in 5'-nucleotidase and especially in alkaline phosphodiesterase I. The results confirm the heterogeneity of rat liver endosomes and substantiate the concept of distinct endosomal compartments.
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PMID:Marker enzymes in rat liver vesicles involved in transcellular transport. 255 96

We have quantified, in cultured rat fibroblasts, the association to the lysosomal membrane of two classical plasma membrane markers, 5'-nucleotidase and alkaline phosphodiesterase I. To isolate highly purified lysosomal preparations, lysosomes were loaded with horseradish peroxidase (2-h cell uptake, 16-h chase) and isolated by isopycnic centrifugation in linear Percoll gradients, followed by a 3,3'-diaminobenzidine-induced density shift in sucrose gradients. Purified lysosomal preparations contained up to 50% of N-acetyl-beta-glucosaminidase of the homogenate. This lysosomal enzyme was enriched 33-fold in the most purified preparations. In the electron microscope, these preparations appeared to be highly purified and only contained organelles filled with diaminobenzidine reaction products. Analysis of purified preparations indicates that 0.5-0.8% of 5'-nucleotidase, but as much as 10.9-14.3% of alkaline phosphodiesterase I activities of the homogenate, are associated with lysosomes. After freezing-thawing, these activities remained essentially membrane-associated. The larger value obtained for alkaline phosphodiesterase I could not be ascribed to other lysosomal enzymes, as no such activity was detected at acidic pH. These two plasma membrane markers are thus unevenly distributed in the lysosomal compartment.
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PMID:Relations between plasma membrane and lysosomal membrane. 2. Quantitative evaluation of plasma membrane marker enzymes in the lysosomes. 282 61


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