Arachidonic acid inhibits a purified and reconstituted glutamate transporter directly from the water phase and not via the phospholipid membrane.

Détails

ID Serval
serval:BIB_BCDE6E1DE54A
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Arachidonic acid inhibits a purified and reconstituted glutamate transporter directly from the water phase and not via the phospholipid membrane.
Périodique
Journal of Biological Chemistry
Auteur⸱e⸱s
Trotti D., Volterra A., Lehre K.P., Rossi D., Gjesdal O., Racagni G., Danbolt N.C.
ISSN
0021-9258
Statut éditorial
Publié
Date de publication
04/1995
Peer-reviewed
Oui
Volume
270
Numéro
17
Pages
9890-9895
Langue
anglais
Résumé
Glutamate is believed to be the major excitatory transmitter in the mammalian central nervous system. Keeping the extracellular concentration of glutamate low, the glutamate transporters are required for normal brain function. Arachidonic acid (AA) inhibits glutamate uptake in relatively intact preparations (cells, tissue slices, and synaptosomes (Rhoads, D.E., Ockner, R. K., Peterson, N. A., and Raghupathy, E. (1983) Biochemistry 22, 1965-1970 and Volterra, A., Trotti, D., Cassutti, P., Tromba, C., Salvaggio, A., Melcangi, R. C., and Racagni, G. (1992b) J. Neurochem. 59, 600-606). The present study demonstrates that the effect of AA occurs also in a reconstituted system, consisting of a purified glutamate transporter protein incorporated into artificial cell membranes (liposomes). The characteristics of the AA effect in this system and in intact cells are similar with regard to specificity, sensitivity, time course, changes in Vmax, and affinity. AA-ethyl ester is inactive, suggesting that the free carboxylic group is required for inhibitory activity. When incubated with proteoliposomes, AA (300 microM, 15 min) mostly partitions to the lipid phase (lipid/water about 95:5). However, uptake inhibition is abolished by rapid dilution (6.5-fold) of the incubation medium (water phase), a procedure that does not modify the amount of AA associated with lipids. On the contrary, inhibition remains sustained if the same dilution volume contains as little as 5 microM AA, a concentration inactive before saturation of liposome lipids with 300 microM AA. The same degree of inhibition (60%) is obtained by 5 microM AA following preincubation with the inactive AA-ethyl ester (300 microM) instead of AA. The lipids apparently inactivate AA by extracting it from the water phase. The results suggest that AA acts on the transporter from the water phase rather than via the membrane. This could be true for other proteins as well since gamma-aminobutyric acid uptake is similarly affected by AA.
Mots-clé
ATP-Binding Cassette Transporters/antagonists &amp, inhibitors, ATP-Binding Cassette Transporters/metabolism, Amino Acid Transport System X-AG, Animals, Arachidonic Acid/pharmacology, Biological Transport, Glutamic Acid/metabolism, Liposomes, Phospholipids/metabolism, Rats, Structure-Activity Relationship, Water, gamma-Aminobutyric Acid/metabolism
Pubmed
Web of science
Création de la notice
24/01/2008 14:37
Dernière modification de la notice
20/08/2019 15:30
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