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 binding of human 125I-labeled HDL3 to purified rat liver and testis plasma membranes was studied. About 50-65% of the total HDL binding in these membranes was abolished by 1% bovine serum albumin in the incubation medium. The remaining albumin-insensitive binding sites, determined in the presence of albumin were associated with plasma membranes; a good correlation was found between the 125I-labeled HDL3 binding and the 5'-nucleotidase activities of the membrane fractions. The binding sites in these tissues were saturable, specific for HDL (not competed for by LDL) and had similar affinities for 125I-labeled HDL3 (Kd, 11.8 micrograms protein/ml for liver and 12.7 micrograms protein/ml for testis membranes); the maximum binding capacity of the testis membranes was higher (1.3 vs. 0.7 microgram protein/mg membrane protein). Egg phosphatidylcholine complexes of both human apolipoprotein A-I and apolipoprotein C's competed for the HDL-binding sites, but phosphatidylcholine vesicles alone did not. Chemical modification of the lysine and arginine residues of apolipoproteins did not affect the interaction of HDL3 with its binding sites. Despite the fact that the HDL-binding sites in these tissues are not specific for apolipoprotein A-I, they may have important physiological roles in lipid transport, as they appear to recognize apolipoprotein-phospholipid complexes.
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PMID:Characterization of high-density lipoprotein binding sites in rat liver and testis membranes. 647 54

A plasma membrane-rich fraction was prepared from guinea pig peritoneal polymorphonuclear leucocytes (PMNs) by a nitrogen cavitation method. Fc receptor activity was measured in the fraction. The activity showed a Kd of 5 X 10(-7) M IgG and a maximum binding of 33 pmol IgG/mg protein when measured with an immune complex made with bovine serum albumin and rabbit anti-(bovine serum albumin) immunoglobulin G. Properties of the Fc receptor in the plasma membrane fraction were similar to that in intact PMNs. It is proposed that the Fc receptor activity and 5'-nucleotidase activity are markers for plasma membranes of these cells.
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PMID:Preparation of polymorphonuclear leucocyte-plasma membranes which show Fc receptor activity. 716 Dec 63

1. The uptake of liposomes containing the photoprotein obelin by rat isolated adipocytes was investigated with the aim of producing liposome-cell fusion, enabling obelin to be introduced into the cytoplasm of intact cells. 2. Incubation of liposomes containing obelin with rat isolated adipocytes resulted in a time-dependent uptake of entrapped obelin by the adipocytes. The uptake by adipocytes (at 2h) of liposomes prepared from phosphatidylcholine, phosphatidylcholine+phosphatidylserine (molar ratio 4:1) and phosphatidylcholine+N-octadecylamine (molar ratio 4:1) was approx. 6, 10 and 10% of original entrapped obelin per g dry wt. of adipocytes respectively. 3. During incubation with adipocytes some of the liposomes became permeable to Ca(2+) ions, resulting in stimulation of obelin luminescence from within the liposomes. This increase in permeability to Ca(2+) seemed to be the result of the interaction of liposomes with the cell membrane. 4. Approx. 50% of liposome uptake could be inhibited by cytochalasin B (500mum). This was consistent with this uptake being the result of endocytosis. The remaining uptake was probably the result of adhesion of liposomes to the cell membrane. 5. In an attempt to detect the presence of cytoplasmic obelin, after incubation of adipocytes with liposomes, a method of causing a rapid rise in cell-membrane permeability to Ca(2+) was developed in which an anti-cell anti-body-complement reaction occurred at the cell membrane. There was no detectable transfer of active obelin into the cell cytoplasm. 6. After incubation of liposomes with adipocytes in the absence of bovine serum albumin, obelin luminescence from a small proportion of liposomes increased (approx. 1.5%) in response to anti-(5'-nucleotidase) antibody plus complement. 7. It was concluded that under the conditions of these experiments, (a) no detectable transfer (<0.1%) of liposome-entrapped obelin to the adipocyte cytoplasm had occurred, (b) an increase in liposome permeability to Ca(2+) occurred during incubation with adipocytes, (c) at least 50% of liposome uptake by adipocytes was the result of endocytosis, presumably into secondary lysosomes, and the remaining uptake was apparently the result of loose attachment of liposomes to the cell surface, and (d) in the absence of bovine serum albumin, a portion of at least one surface antigen, the ectoenzyme 5'-nucleotidase, was transferred from the adipocyte membrane to the liposome membrane.
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PMID:Uptake of liposomes containing the photoprotein obelin by rat isolated adipocytes. Adhesion, endocytosis or fusion? 723 27

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

PD 138142-15 is a substituted urea hypolipidemic and potential anti-atherosclerotic agent. To determine the toxicity of PD 138142-15, beagle dogs were given oral doses of 1, 10, 30, and 100 mg/kg daily for 13 weeks. Two animals at 100 mg/kg were euthanized during Week 5 due to poor condition. Clinical findings included decreased serum albumin at > or = 30 mg/kg, and increased ALP (up to 30-fold) and 5'-nucleotidase activities (up to 9-fold) at doses > or = 10 mg/kg. ALT and AST activities were elevated only at 100 mg/kg. There was a two- to threefold increase in cytochrome P450 content of hepatic microsomes from all treated animals and increases in liver weights at 10 mg/kg and above. Hepatic changes included hepatocellular hypertrophy and increased cytoplasmic eosinophilia at > or = 10 mg/kg; single cell necrosis of hepatocytes was noted in moribund animals. ACTH-stimulated cortisol levels were decreased at 30 and 100 mg/kg. Adrenal cholesterol esters were decreased at 10 mg/kg and above, while total adrenal cholesterol was decreased at > or = 30 mg/kg. These changes correlated with adrenal cortical zonal atrophy, principally of the zona fasciculata and zona reticularis, present at 30 and 100 mg/kg. Plasma concentrations of PD 131842-15 increased with increasing dose; plasma levels were significantly lower during Week 12 than those on Day 1, possibly due to autoinduction. Overt hepatotoxicity occurred at 100 mg/kg, whereas hepatic changes at 10 and 30 mg/kg were consistent with cytochrome P450 induction. The hepatic lesions were reversible within 4 weeks, while adrenal lesions were still evident after 4 weeks without treatment.
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PMID:Hepatic and adrenal toxicity of a novel lipid regulator in beagle dogs. 758 16

Except for increased serum alkaline phosphatase (AP) levels, the changes in liver function test (LFT) values during normal pregnancy have not been clearly established, mainly because most studies do not include matched controls. We therefore measured the serum values of routine liver tests including 5'-nucleotidase and total bile acids in 103 healthy pregnant women (first trimester, n = 34; second trimester, n = 36; third trimester, n = 33) and in 103 age-matched controls not receiving oral contraception. Fasting blood samples were taken. Because of hemodilution, serum albumin levels were significantly lower during all trimesters. As expected, AP activity was significantly higher in the third trimester. Serum aspartate transaminase (AST) activity and total bile acid (TBA) concentrations did not differ between pregnant and nonpregnant women. Serum alanine transaminase (ALT) activity was slightly higher in the second-trimester pregnant women than in controls (6.8 +/- 4.5 vs. 8.2 +/- 5.8, P = .04), although all values remained within normal limits. In pregnant women, total and free bilirubin concentrations were significantly lower during all three trimesters, as was conjugated bilirubin during the second and third trimesters. Serum gamma-glutamyl transpeptidase (GGT) activity was significantly lower in the second and third trimesters. Serum 5'-nucleotidase activity was slightly but significantly higher in the second and third trimesters. The knowledge of these results is useful for the interpretation of LFT values and the management of liver diseases during pregnancy.
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PMID:Liver function tests in normal pregnancy: a prospective study of 103 pregnant women and 103 matched controls. 862 Nov 29


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