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

---

Query: EC:3.1.3.5 (5'-nucleotidase)
3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plasma membranes isolated from HeLa cells on discontinuous sucrose gradients were assayed for their capacity to elute and uncoat coxsackievirus B3 at 37 C. Because the viral receptors are limited to the surface of HeLa cells, the addition of radioactively labeled virus to the cells prior to cell homogenization provided a useful marker for locating the plasma membranes during the fractionation procedure. Four bands were formed on the discontinuous sucrose gradients with approximately 70% or more of the membrane-associated viral label being recovered in the most dense bands, designated as bands 3 and 4. Bands 3 and 4 also possessed the plasma membrane marker enzymes, Na+, K+ adenosine triphosphatase and 5'-nucleotidase and revealed typical structures characteristic of plasma membranes as revealed by electron microscopy. Pelleted and washed membranes from band 3 both eluted and uncoated B3 32P-labeled virus, whereas membranes from band 4 eluted virus but failed to uncoat it. The membranes from band 4 were shown to inhibit the viral uncoating activity when mixed with membranes of band 3. Characteristically, unfractionated homogenates of cell membranes eluted but did not uncoat virus. The finding of a naturally occurring inhibitor of virus uncoating provides for the first time a way to distinguish between the membrane activities of virus elution and virus uncoating. The inhibitor remains to be characterized.
...
PMID:Elution and uncoating of Coxsackievirus B3 by isolated HeLa cell plasma membranes. 12 11

Membrane glycoproteins have been studied in the normal lactating mammary gland and R3230 AC mammary tumor of the rat. Plasma membrane-enriched fractions were obtained from these tissues by discontinuous sucrose gradient centrifugation of a microsomal preparation from the tissue homogenates. The lightest membrane fractions (F-1 and F-2) have the greatest enrichment of plasma membrane markers, with a 14- to 20-fold purification of 5'-nucleotidase and Na+-K+ -adenosine triphosphatase over the homogenate values in both tumor and normal tissues for F-1. Electron microscopy shows smooth membrane vesicles for these fractions. Polypeptide analysis by acrylamide gel electrophoresis shows essentially the same patterns for F-1 and F-2 and only relatively minor differences between membrane components of tumor and normal tissues. Glycoprotein analysis of the polyacrylamide gels by periodate-Schiff staining indicates more dramatic differences. Membrane Fraction F-1 from normal tissue contains two major glycoproteins, GP-II and GP-III, while Fractions F-2 and F-3 contain an additional glycoprotein, GP-I, with a higher apparent molecular weight. In the tumor, the component corresponding to GP-III is decreased or absent and a new component GP-IV is seen at a lower apparent molecular weight.
...
PMID:Membrane glycoprotein differences between normal lactating mammary tissue and the R3230 AC mammary tumor. 12 79

NIL 8 hamster fibroblast cells were labeled by lactoperoxidase-catalyzed iodination. Their membranes were fractionated by sedimentation-rate and isopycnic zonal centrifugation. All the iodinated proteins except the very prominently labeled high molecular weight protein (greater than 200,000 daltons) were located in a fraction identified enzymically and compositionally as plasma membrane. The high molecular weight protein that was previously shown to be sensitive to virus transformation (Hynes, 1973) is concentrated in a very high density particle (rho equals 1.253-1.259) which contains mainly carbohydrate and protein and very low levels of lipid. 5'-nucleotidase was the only enzyme reproducibly demonstrated in this fraction, and electron micrographs revealed a predominantly amorphous morphology together with a few membraneous structures. The iodine label in this fraction was very sensitive to trypsinization prior to homogenization. All the available evidence indicates that this fraction is derived from the surface coat. Mitochondria, nuclei, and soluble protein were labeled to an insignificant extent. The presence of the iodinated surface proteins associated with the endoplasmic reticulum fraction is discussed in the light of these results.
...
PMID:The location of proteins labeled by the 125I-lactoperoxidase system in the NIL 8 hamster fibroblast. 12 85

The ionic influence and ouabain sensitivity of lymphocyte mg-2+-atpase and Mg-2+-(Na+ +K+)-activated ATPase were studied in intact cells, microsomal fraction and isolated plasma membranes. The active site of 5'-nucleotidase and Mg2+-ATPase seemed to be localized on the external side of the plasma membrane whereas the ATP binding site of (Na+ +K+)-ATPase was located inside the membrane. Concanavalin A induced an early stimulation of Mg2+-APTase and (Na+ +K+)-ATPase both on intact cells and purified plasma membranes. In contrast, 5'-nucleotidase activity was not affected by the mitogen. Although the thymocyte Mg2+-ATPase activity was 3-5 times lower than in spleen lymphocytes, it was much more stimulated in the former cells (about 40 versus 20%). (Na+ +K+)-ATPase activity was undectectable in thymocytes. However, in spleen lymphocytes (Na+ +K+)-ATPase activity can be detected and was 30% increased by concanavalin A. Several aspects of this enzymic stimulation had also characteristic features of blast transformation induced by concanavalin A, suggesting a possible role of these enzymes, especially Mg2+-ATPase, in lymphocyte stimulation.
...
PMID:Effect of concanavalin A on membrane-bound enzymes from mouse lymphocytes. 12 86

1. A method is described for the isolation of a plasma membrane fraction from rat ventral prostate. This fraction is greatly enriched in (Na-", K-+)-ATPase but also contains a small amount of Mg-2+-ATPase and 5'-nucleotidase activities. 2. The activity ratio (Mg-2+ plus Na-+ plus K-+/Mg-2+ or Mg-+ plus Na-+) of the plasma membrane (Na-+, K-+)-ATPase was 1.7. The enzyme system specifically requires ATP as substrate and is inhibited by Ca-2+ or ouabain.
...
PMID:Preparation of prostatic plasma membranes Distribution of (Na-+, K-+)-ATPase and Mg-2+-ATPase in the rat ventral prostate. 12 95

Electron microscopic cytochemical localization of Mg++-activated adenosine triphosphatase (Mg++-ATPase) and 5-nucleotidase (AMPase) was investigated in bile canaliculus-rich and bile duct-containing fractions isolated from rat liver. Comparative cyochemical studies between prefixed and non-prefixed fractions revealed that the activity of both enzymes could be detected in the fractions under appropriate experimental conditions. However, the cytochemical activity of AMPase was much more sensitive to glutaraldehyde than that of Mg++-ATPase. Mg++-ATPase and AMPase reaction products were localized primarily on bile canalicular microvilli, that is, along the outer (luminal) surface of canalicular plasma membranes, but they were never observed on bile ductal microvilli. AMPase was also detectable on lateral hepatic plasma membranes. Mg++-ATPase demonstrated by the cytochemical technique described is a reliable enzyme marker for isolated bile canalicular membranes. At high magnification, Mg++-ATPase reaction product was also observed on the microfilaments surrounding isolated bile canaliculi. The possibility that the reaction product on the pericanalicular microfilaments may result from the hydrolysis of ATP byan actomyosin ATPase-like enzyme associated with these filaments is briefly discussed.
...
PMID:Electron microscopic cytochemical characterization of bile canaliculi and bile ducts in vitro. 12 97

1. A procedure was developed for the preparation of plasma membranes from experimental granulation tissue of the rat without the addition of enzymes. The yield is better than 20% and the purification at least tenfold. 2. Values are given for the activities of 5'-nucleotidase, Na-+, k-+-activated Mg-2+dependent adenosine triphosphatase and leucine beta-naphthylamidase, for lipid composition, and for the gel-electrophoretic patterns of proteins and glycoporteins in the membrane preparations. 3. The plasma membranes from the mature granulation tissue contain proportionally more protein in the lipid phase, but the specific activities of 5'-nucleotidase and Na-+,K-+-activated Mg-2+-dependent adenosine triphosphatase are smaller than in the proliferating tissue. Certain differences were repeatedly observed in the gel-electrophoretic patterns of the developmental phases. 4. The plasma membranes from the granulation tissue were compared with those from rat peritoneal macrophages and from embryonic-chick tendon cells.
...
PMID:Plasma membranes from experimental granulation tissue. 12 81

1. Six rat liver plasma-membrane subfractions of different density and morphological, enzymic and chemical properties were prepared from homogenates by a combination of differential, rate-zonal and density-gradient centrifugation. They consisted of three vesicular 'light' subfractions of density 1.12-1.13 and three 'heavy' subfractions of density 1.16-1.18 containing membrane strips and intercellular junctions. 2. All six subfractions contained a basal adenylate cyclase activity. One of the 'light' subfractions that showed the highest glucagon-stimulated adenylate cyclase activity was identified as deriving form the blood-sinusoidal face of the hepatocyte. This subfraction, unlike the others, was contaminated by Golgi components, as indicated by its morphological properties and the presence of galactosyl- and sialyl-transferase activities. 3. All the six subfractions showed high activities of the following plasma-membrane marker enzymes: 5'-nucleotidase, alkaline phosphodiesterase (nucleotide pyrophosphatase), alkaline phosphatase, leucine naphthylamidase and Mg2+-activated adenosine triphosphatase. A 'light' subfraction that showed the highest specific activities of all the above marker enzymes, but lacked a glucagon-stimulated adenylate cyclase activity, was identified as deriving from the bile-canalicular face of the hepatocyte. 4. The 'heavy' subfractions, which showed generally the lowest activities of the above plasma-membrane enzyme markers, and were characterized by the presence of desmosomes and gap junctions, were taken to originate from the contiguous faces of the hepatocyte. 5. The protein composition of the six subfractions was generally similar, as shown by polyacrylamide-gel electrophoresis. Differences in the amounts of various protein and glycoprotein bands among the subfractions correlated with their morphology, enzymic composition and sialic acid content. 6. Hormonal and histochemical evidence supporting the identification of a bile-canalicular subfraction, a blood-sinusoidal subfraction and contiguous-face subfractions is discussed.
...
PMID:Functional polarity of the rat hepatocyte surface membrane. Isolation and characterization of plasma-membrane subfractions from the blood-sinusoidal, bile-Canalicular and contiguous surfaces of the hepatocyte. 12 84

A pronounced effect of concanavalin A (Con A) upon activity of ecto-5'-nucleotidase of intact C6 glioma cells in culture has been demonstrated. A near linear rate of decrease in 5'-nucleotidase activity was observed upon treatment with concentrations of Con A up to 0.25 muM. Nonspecific phosphatase activity and Ca2+-dependent ATPase activity were not inhibited by Con A treatment of the cells. Of the total 5'-nucleotidase activity of C6 cells (Vmax = 5.0 mumol of Pi liberated/mg of cell protein/hour), approximately 20% still remained after treatment with high concentrations of Con A. The inhibitory effect of Con A operated to reduce substantially Vmax for ecto-5'-nucleotidase. Inhibition was reversed by briefly incubating the Con A-treated cells with alpha-methyl-D-glucoside, or alpha-methyl-D-mannoside, the later being more effective. These findings suggest that a relatively specific, reversible, inhibition of ecto-5'-nucleotidase results from Con A binding to the surface of the intact cultured mammalian cells.
...
PMID:Concanavalin A inhibition of ecto-5'-nucleotidase of intact cultured C6 glioma cells. 12 59

The influence of the mode of preparation upon some of the characteristics of white adipose tissue plasma membranes and microsomes has been reported. Plasma membrane fractions prepared from mitochondrial pellet were shown to have higher specific activities of (Mg2+ + Na+ + K+)-ATPase than plasma membranes originating in crude microsomes. Isolation of fat cells by collagenase treatment was found to result in a decrease in specific activity of the plasma membrane enzymes; in plasma membranes prepared from isolated fat cells, the specific activity values obtained for (Mg2+ + Na+ +k+)-ATPase and 5'-nucleotidase were only 42% and 6.3% respectively of those obtained in plasma membranes prepared from whole adipose tissue. Purification of whole adipose tissue crude microsomes by hypotonic treatment caused extensive solubilization of the endoplasmic reticulum marker enzymes, NADH oxidase and NADPH cytochrome c reductase. The lability of endoplasmic reticulum marker enzymes, however, was found to be greatly diminished in the preparations from isolated fat cells. The possibility that NADH oxidase and NADPH cytochrome c reductase activities found in the plasma membranes are microsomal enzymes adsorbed by the plasma membranes is discussed. The peptide patterns as well as the NADH oxidase and NADPH cytochrome c reductase activity patterns of plasma membranes and purified microsomes were compared by means of sodium dodecyl sulfate or Triton X-100 polyacrylamide gel electrophoresis.
...
PMID:Comparison of plasma membranes and endoplasmic reticulum fractions obtained from whole white adipose tissue and isolated adipocytes. 12 89


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---