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5'-Nucleotidase activity of lymphocyte plasma membranes. Effect of concanavalin A] |
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| Authors: | J Dornand C Réminiac J C Mani |
| Affiliation: | ER CNRS n° 62, Ecole Nationale Supérieure de Chimie, 8, rue de l''Ecole Normale, 34075 Montpellier Cedex, France |
| Abstract: | The 5'-nucleotidase properties of isolated lymphocyte plasma membranes from young pig mesenteric nodes are described; nucleosides-5'-monophosphates are the substrates of this specific enzyme. Concanavalin A inhibits this enzyme; on the same membranes this mitogen does not affect alkaline phosphatase and activates the membrane bound (Ca2+) ATPase. The 5'-nucleotidase inhibition is due to a specific interaction of Con A with carbohydrate groups of the membrane; its high positive cooperativity suggests that the lectin promotes reorganization of the membrane bound 5'-nucleotidase. Solubilization of the 5'-nucleotidase does not prevent the effect of Con A and the solubilized enzyme is firmly bound by Con A-Sepharose 4B; these results suggest that Con A inhibits the enzyme by a direct interaction and that 5'-nucleotidase can be considered as an eventual receptor for the lectin. |
| Keywords: | 5′-AMP 5′-adénosine monophosphate 5′-CMP 5′-cytosine monophosphate 5′-GMP 5′-guanosine monophosphate 5′-IMP 5′-inosine monophosphate 5′-dAMP 5′-désoxyadénosine monophosphate 5′-dCMP 5′-désoxycytosine monophosphate PNP paranitrophénol PNPP paranitrophényl phosphate DOC désoxycholate de sodium Con A concanavaline A Pi phosphate inorganique TCA acide trichloracétique EDTA acide éthylène-diamine-tétraacétique EGTA acide éthylèneglycol-bis-(2-aminoéthyl)- té-traacétique |
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