%0 Journal Article %A U Klockner %A T Storck %A M Conradt %A W Stoffel %T Functional properties and substrate specificity of the cloned L- glutamate/L-aspartate transporter GLAST-1 from rat brain expressed in Xenopus oocytes %D 1994 %R 10.1523/JNEUROSCI.14-10-05759.1994 %J The Journal of Neuroscience %P 5759-5765 %V 14 %N 10 %X The rat brain L-glutamate/L-aspartate transporter GLAST-1 is a member of a family of Na(+)-dependent high-affinity L-glutamate transporters proposed to be involved in the termination and modulation of excitatory neurotransmitter signals. Application of electrophysiological and radiotracer techniques on Xenopus oocytes expressing cloned GLAST-1 revealed that the apparent Km value of the transporter for L-glutamate and Na+ ions did not depend on voltage while the maximal transport rate increased with more negative potentials, indicative of a low-field access channel. The apparent Km value of the transporter for L- glutamate depends on the Na+ concentration, suggesting that substrate and ions are transported by GLAST-1 in a simultaneous manner. All of the L-glutamate uptake blockers tested either were substrates or did not affect the current induced by L-glutamate. The changes in the amplitude of the current induced by simultaneous application of two substrates can be interpreted by a competition for one binding site. %U https://www.jneurosci.org/content/jneuro/14/10/5759.full.pdf