Glutamate uptake by brain synaptic vesicles. Energy dependence of transport and functional reconstitution in proteoliposomes.

摘要: The dependence of glutamate uptake on ATP-generated proton electrochemical potential was studied in a highly purified preparation synaptic vesicles from rat brain. At low chloride concentration (4 mM), the pump present generated large membrane (inside-positive), associated with only minor acidification. Under these conditions, rate L-[3H]glutamate maximal. In addition, L-glutamate induced acidification vesicle interior. D-Glutamate produced 40% effect, and L-aspartate or gamma-aminobutyric acid less than 5%. initial glutamate-induced increased increasing concentration. It saturable showed first-order kinetics (KM = 0.32 mM). Correspondingly, small reduction potential. ATP hydrolysis unaffected. comparison, had no effect resealed membranes chromaffin granules. high (150 vesicular pH difference, change by low. For reconstitution, proteins were solubilized detergent sodium cholate, supplemented brain phospholipids, incorporated into liposomes. Proton activities proteoliposomes properties similar to those intact indicating that carrier reconstituted functionally active form. is concluded dependent all components required for are integral parts membrane.