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)

Previous immunolabeling studies (Roman, L.M., and A.L. Hubbard, 1983, J. Cell Biol., 96:1548-1558; Roman, L.M., and A.L. Hubbard, 1984, J. Cell Biol., 98:1488-1496, companion paper) established leucine aminopeptidase (LAP) as a specific marker for the bile canalicular (BC) domain of the rat hepatocyte plasma membrane (PM). In this study, we have isolated membrane from a sonicated PM vesicle fraction using anti-LAP-coated Staphylococcus aureus cells as a solid-phase immunoadsorbent. The extent and specificity of the immunoadsorption were assessed by following the behavior of LAP (the BC marker) and 32P-labeled membrane phospholipids (a uniform membrane marker). The BC fraction obtained was significantly enriched in LAP (yield: greater than 70% of PM-LAP). Alkaline phosphatase, 5'-nucleotidase, and a 110,000-dalton glycoprotein, HA-4, were enriched in the BC fraction to the same extent as LAP (enzyme or antigen/LAP = 1.0). However, alkaline phosphodiesterase I was not enriched to the same degree (enzyme/LAP = 0.5). Contamination of this BC fraction by membrane derived from the sinusoidal domain and endoplasmic reticulum, as determined from the distribution of the asialoglycoprotein receptor and NADH cytochrome c reductase, respectively, was small (less than 13%).
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PMID:A domain-specific marker for the hepatocyte plasma membrane. III. Isolation of bile canalicular membrane by immunoadsorption. 637 Oct 22

Rat liver organelles involved in receptor-mediated endocytosis were labeled with a conjugate of galactosylated BSA to horseradish peroxidase [( 3H]galBSA-HRP), injected 10 min before sacrifice. These organelles were recovered at low density (1.11-1.13 g/ml) in sucrose gradients (Quintart, J., P. J. Courtoy, J. N. Limet, and P. Baudhuin, 1983, Eur. J. Biochem., 131:105-112). Upon incubation of such low density fractions in 3,3'-diaminobenzidine (DAB) and H2O2 and equilibration in a second sucrose gradient, galBSA-HRP-containing particles selectively shifted towards heavier densities (Courtoy, P. J., J. Quintart, and P. Baudhuin, 1984, J. Cell Biol., 98:870-876, companion paper), resulting in up to 250-to 300-fold purification with respect to the homogenate. The most purified preparations, wherein DAB-stained structures represented approximately 85% of the total volume of particles, contained only trace activities of enzymes usually regarded as markers for other subcellular entities. These minor activities could reflect either contamination or true enzyme association to the ligand-containing structures. Considering the latter hypothesis, at most 1.0% of alkaline phosphodiesterase I and 2.6% of 5'-nucleotidase (markers for plasma membrane), 3.6% of N-acetyl-beta-glucosaminidase (lysosomes), and 6.0% of galactosyltransferase (Golgi complex) from the homogenate would be associated with the whole population of ligand-containing organelles. After DAB cytochemistry on liver fixed 10 min after galBSA-HRP injection, ligand-containing structures accounted for 0.78-0.89% of the fractional volume of the hepatocytes and displayed a membrane area of 2,100 cm2/cm3, compared with 6,700 cm2/cm3 for the pericellular membrane. Altogether, our data support the hypothesis that these ligand-containing organelles are structurally distinct from plasma membrane, lysosomes, and Golgi complex.
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PMID:Receptor-mediated endocytosis in rat liver: purification and enzymic characterization of low density organelles involved in uptake of galactose-exposing proteins. 669 90

A method has been developed for routine high yield separation of canalicular (cLPM) from basolateral (blLPM) liver plasma membrane vesicles of rat liver. Using a combination of rate zonal floatation (TZ-28 zonal rotor, Sorvall) and high speed centrifugation through discontinuous sucrose gradients, 9-16 mg of cLPM and 15-28 mg of blLPM protein can be isolated in 1 d. cLPM are free of the basolateral markers Na+/K+-ATPase and glucagon-stimulatable adenylate cyclase activities, but are highly enriched with respect to homogenate in the "canalicular marker" enzyme activities leucylnaphthylamidase (48-fold), gamma-glutamyl-transpeptidase (60-fold), 5'-nucleotidase (64-fold), alkaline phosphatase (71-fold), Mg++-ATPase (83-fold), and alkaline phosphodiesterase I (116-fold). In contrast, blLPM are 34-fold enriched in Na+/K+-ATPase activity, exhibit considerable glucagon-stimulatable adenylate cyclase activity, and demonstrate a 4- to 15-fold increase over homogenate in the various "canalicular markers." cLPM have a twofold higher content of sialic acids, cholesterol; and sphingomyelin compared with blLPM. At least three canalicular-(130,000, 100,000, and 58,000 mol wt) and several basolateral-specific protein bands have been detected after SDS PAGE of the two LPM subfractions. Specifically, the immunoglobin A-binding secretory component is restricted to blLPM as demonstrated by immunochemical techniques. These data indicate virtually complete separation of basolateral from canalicular LPM and demonstrate multiple functional and compositional polarity between the two surface domains of hepatocytes.
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PMID:Structural and functional polarity of canalicular and basolateral plasma membrane vesicles isolated in high yield from rat liver. 669 96

The administration of the bone-seeking isotope, 89Sr, to mice results in severe monocytopenia without any apparent effect on the numbers of resident peritoneal macrophages (Mphi). An explanation for this dichotomy was sought by determining whether the residual blood monocytes were still an effective source of Mphi after 89Sr treatment. Stem cell enumeration showed that a 90% fall in bone marrow macrophage colony-forming cells after 89Sr was accompanied by a 10-fold rise in splenic M-CFC. Splenectomy performed before 89Sr treatment, however, resulted in little additional monocytopenia and had no affect on the numbers of resident peritoneal Mphi even when sampling was extended to 31 days, an interval beyond the accepted half-time for peritoneal Mphi. Intraperitoneal injections of thioglycollate or Corynebacterium parvum elicited few or no monocyte-Mphi during respective intervals of 4 and 7 days. Elicitation with thioglycollate was attempted in tritiated thymidine-labeled mice 26 days after 89Sr. Four days later only a 2-fold increase in labeled peritoneal Mphi was found in the 89Sr-treated mice compared with a 150-fold increase in the controls. Studies of the ectoenzymes 5'-nucleotidase, alkaline phosphodiesterase I, and leucine aminopeptidase in such elicitation experiments suggested that the observed changes in activities reflected the direct stimulation of resident Mphi rather than monocyte immigration. Overall, the results indicate that treatment with 89Sr distinguishes two large populations of Mphi on the basis of their dependence on bone marrow. Mphi of inflammation reflect the monocytopenia and are severely and rapidly depleted by such treatment. The maintenance of resident type Mphi, on the other hand, appears to be independent of both the state of the bone marrow and the level of monocytes in the blood.
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PMID:Differential effects of chronic monocyte depletion on macrophage populations. 688 84

The role of phosphatidylinositol-specific phospholipase C (PIase C) in a) the enigmatic phosphatidylinositol (PI) turnover and b) in our understanding of membrane enzyme-PI interactions is the subject matter of this article. PIase C is present in both procaryotes and eukaryotes. This enzyme is considered to be involved in the cells PI breakdown which occurs in response to several external stimuli. Recent information on the physical properties, Ca2+ requirement, cellular localization and modulation of the activity of PIase C of mammalian systems can help to evaluate the PI turnover from a new angle. Existing evidence suggests that Ca2+-dependent PI breakdown is probably mediated through the cytosolic and particulate PIase C while a Ca2+ independent pathway is catalyzed by a lysosomal enzyme. Apparently PI turnover may be operating through more than one mechanism. The association of this phenomenon with a membrane receptor event linked with "Ca2+ gating" may have to be reconsidered. Modulation of the PIase C activity by unsaturated amphiphiles or the presence of this enzyme in different physico-chemical forms could be a potential regulatory feature. Hydrolysis of membrane PI of a number of cells and tissues by the bacterial PIase C has been shown to cause substantial release of acetylcholinesterase, alkaline phosphatase and 5'-nucleotidase in free, soluble form. Other membrane enzymes, e.g., alkaline phosphodiesterase I, L-leucyl-beta naphthyl amidase and Ca2+ or Mg2+ ATPase are not affected. These results indicate a specific interaction between PI and certain enzymes in membranes. The chemical nature of this linkage, whether it is covalent or non-covalent, has also been explored and has provided intriguing insight into this phenomenon. New findings also indicate that hydrolysis of PI by PIase C also can cause modifications in membrane-enzyme activities, e.g., adenylate cyclase.
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PMID:Minireview. Phosphatidylinositol specific phospholipases C. 708 67

Preparations enriched with plasmalemmal, outer mitochondrial, or Golgi complex membranes from rat liver were subfractionated by isopycnic centrifugation, without or after treatment with digitonin, to establish the subcellular distribution of a variety of enzymes. The typical plasmalemmal enzymes 5'-nucleotidase, alkaline phosphodiesterase I, and alkaline phosphatase were markedly shifted by digitonin toward higher densities in all three preparations. Three glycosyltransferases, highly purified in the Golgi fraction, were moderately shifted by digitonin in both this Golgi complex preparation and the microsomal fraction. The outer mitochondrial membrane marker, monoamine oxidase, was not affected by digitonin in the outer mitochondrial membrane marker, monoamine oxidase, was not affected by digitonin in the out mitochondrial membrane preparation, in agreement wit its behavior in microsomes. With the exception of NADH cytochrome c reductase (which was concentrated in the outer mitochondrial membrane preparation), typical microsomal enzymes (glucose-6-phosphatase, esterase, and NADPH cytochrome c reductase) displayed low specific activities in the three preparations; except for part of the glucose-6-phosphatase activity in the plasma membrane preparation, their density distributions were insensitive to digitonin, as they were in microsomes. The influence of digitonin on equilibrium densities was correlated with its morphological effects. Digitonin induced pseudofenestrations in plasma membranes. In Golgi and outer mitochondrial membrane preparations, a few similarly altered membranes were detected in subfractions enriched with 5'-nucleotidase and alkaline phosphodiesterase I. The alterations of Golgi membranes were less obvious and seemingly restricted to some elements in the Golgi preparation. No morphological modification was detected in digitonin-treated outer mitochondrial membranes. These results indicate that each enzyme is associated with the same membrane entity in all membrane preparations and support the view that there is little overlap in the enzymatic equipment of the various types of cytomembranes.
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PMID:Analytical study of microsomes and isolated subcellular membranes from rat liver VIII. Subfractionation of preparations enriched with plasma membranes, outer mitochondrial membranes, or Golgi complex membranes. 725 62

The plasma membrane of the hepatoma cell line, HTC cells, has been characterized and purified by cell fractionation techniques. In the absence of true 5'-nucleotidase in HTC cells, alkaline phosphodiesterase I has been used as a marker enzyme, following conclusions gained from differential and isopycnic centrifugation studies (Lopez-Saura, P., Trouet, A. and Tulkens, P. (1978) Biochim. Biophys. Acta 543, 430-449). To confirm this localization, HTC cells were exposed to anti-plasma membrane IgG at 4 degrees C and fractionated. Alkaline phosphodiesterase I and IgG showed superimposable distribution patterns in linear sucrose gradients. Alkaline phosphodiesterase I is, however, only poorly resolved from enzyme markers of other organelles, especially NADPH-cytochrome c reductase (endoplasmic reticulum) and galactosyltransferase (Golgi complex). Maximal purification from the homogenate is only 13-fold, on a protein basis, even when using a microsomal fraction (67 and 13% of alkaline phosphodiesterase I and protein, respectively) as the starting material. Improved resolution can be obtained after the addition of small quantities of digitonin (equimolar with respect to the cholesterol content). Digitonin increases the buoyant density of alkaline phosphodiesterase I by approx. 0.05 g/cm3, whereas the buoyant densities of galactosyltransferase and NADPH-cytochrome c reductase are increased only by 0.03 and 0.015 g/cm3, respectively. Accordingly, a procedure has been designed which yields a fraction containing 22.8% of alkaline phosphodiesterase I with a purification of 21-fold on a protein basis. The content of NADPH-cytochrome c reductase and galactosyltransferase is 1.2 and 2.1%, respectively. Electron microscopy shows smooth surface membrane elements and vesicles, with only occasional other recognizable elements.
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PMID:Analytical characterization and purification of plasma membrane from cultured hepatoma cells (HTC cells). 726 68

The conjugated trihydroxy bile salts glycocholate and taurocholate removed approx. 20--30% of the plasma-membrane enzymes 5'-nucleotidase, alkaline phosphatase and alkaline phosphodiesterase I from isolated hepatocytes before the onset of lysis, as judged by release of the cytosolic enzyme lactate dehydrogenase. The conjugated dihydroxy bile salt glycodeoxycholate similarly removed 10--20% of the 5'-nucleotidase and alkaline phosphatase activities, but not alkaline phosphodiesterase activity; this bile salt caused lysis of hepatocytes at approx. 10-fold lower concentrations (1.5--2.0mM) than either glycocholate or taurocholate (12--16mM). At low concentrations (7 mM), glycocholate released these enzymes in a predominantly particulate form, whereas at higher concentrations (15 mM) glycocholate further released these components in a predominantly 'soluble' form. Inclusion of 1% (w/v) bovine serum albumin in the incubations had a small protective effect on the release of enzymes from hepatocytes by glycodeoxycholate, but not by glycocholate. These observations are discussed in relation to the possible role of bile salts in the origin of some biliary proteins.
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PMID:Effects of bile salts on the plasma membranes of isolated rat hepatocytes. 739 66

Membrane-bound nucleotidases and phosphodiesterases are critical regulators of extracellular nucleic acid processing. We previously demonstrated that mesangial cell 5'-nucleotidase was an ectoenzyme, the expression of which was stimulated by macrophage-secreted products. We show in the present study that rat mesangial cell alkaline phosphodiesterase I is also an ectoenzyme characterized by a Km value of 0.41 mM and a Vmax of 20.8 nmol min-1 mg-1. Treatment of mesangial cells by dexamethasone increased alkaline phosphodiesterase I activity in a dose- and time-dependent manner. Maximal increase (x1.5) occurred after treatment with 1 microM dexamethasone for 5 days. Cycloheximide and RU 38486, a glucocorticoid receptor antagonist, suppressed the dexamethasone-induced increase in alkaline phosphodiesterase I activity. 5'-Nucleotidase activity was not modified by dexamethasone under similar conditions of study. In contrast with 5'-nucleotidase, alkaline phosphodiesterase I expression remained unchanged in the presence of macrophage-conditioned medium or during cocultures of mesangial cells with macrophages. Interleukin-1, tumor necrosis factor, cyclic adenosine monophosphate and adenosine analogues also activated 5'-nucleotidase whereas they were inactive on alkaline phosphodiesterase I. These results suggest that extracellular DNA trapped in the mesangial area of the glomerular capillaries may be processed in part at the cell surface by alkaline phosphodiesterase I and that such an event may be regulated by glucocorticoids. They also show that alkaline phosphodiesterase I and 5'-nucleotidase obey a different regulation.
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PMID:Characterization and control of expression of cell surface alkaline phosphodiesterase I activity in rat mesangial glomerular cells. 753 14

Prostasomes are human prostate derived organelles that were isolated from both prostatic fluid and seminal plasma for the present study. Specific activities were determined for prostasome membrane-associated enzymes, alkaline phosphatase (ALP), 5'-nucleotidase (5'NT), and alkaline phosphodiesterase I (APD). The mode of their membranous anchoring was studied by treatment of prostasomes with phosphoinositol-specific phospholipase C (PIPLC) and different detergents. A substantial amount of ALP (50%) and 5'NT (31%) was released by incubation of prostasomes with 2 U/ml of PIPLC contrary to the small amount of APD (12%) released by the same treatment. After PIPLC treatment, the enzymes were recovered in the aqueous phase after phase repartition in Triton X-114 indicating that PIPLC removed the hydrophobic domain converting the enzymes from membrane-linked to aqueous soluble forms. Octyl glycoside was the most efficient one among different detergents to solubilize the enzymes from the prostasome membrane. Both ALP and 5'NT were resistant to the treatment with Triton X-100 and Triton X-114. These results suggest that ALP, 5'NT, and APD are more or less extensively linked to the prostasome membrane via a glycophosphoinositide anchor.
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PMID:Association of some hydrolytic enzymes with the prostasome membrane and their differential responses to detergent and PIPLC treatment. 763 87


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