Excitatory Amino Acid Transporters (EAATs) are plasma membrane proteins responsible for maintenance of low extracellular concentrations of glutamate in the CNS. Dysfunction in their activity is implicated in various neurological disorders. Glutamate transport by EAATs occurs through the movement of the central transport domain relative to the scaffold domain in the EAAT membrane protein. Previous studies suggested that residues located within the interface of these two domains in EAAT2, the main subtype of glutamate transporter in the brain, are involved in regulating transport rates. We used mutagenesis, structure-function relationship, surface protein expression and electrophysiology studies, in transfected COS-7 cells and oocytes, to examine residue glycine at position 298, which is located within this interface. Mutation G298A results in increased transport rate without changes in surface expression, suggesting a more hydrophobic and larger alanine results in facilitated transport movement. The increased transport rate does not involve changes in sodium affinity. Electrophysiological currents show that G298A increase both transport and anion currents, suggesting faster transitions through the transport cycle. This work identifies a region critically involved in setting the glutamate transport rate.

兴奋性氨基酸转运蛋白 (EAAT) 是质膜蛋白，负责维持 CNS 中低细胞外谷氨酸浓度。它们的活动功能障碍与各种神经系统疾病有关。EAAT 的谷氨酸转运是通过中央转运结构域相对于 EAAT 膜蛋白中的支架结构域的运动发生的。先前的研究表明，位于大脑中谷氨酸转运蛋白的主要亚型 EAAT2 中这两个结构域界面内的残基参与了转运速率的调节。我们在转染的 COS-7 细胞和卵母细胞中使用诱变、结构-功能关系、表面蛋白表达和电生理学研究来检查位于该界面内的 298 位残留甘氨酸。突变 G298A 导致转运速率增加，但表面表达没有变化，这表明疏水性更强和丙氨酸更大，从而促进了转运运动。增加的转运速率不涉及钠亲和力的变化。电生理电流表明 G298A 增加了运输和阴离子电流，表明通过运输周期的转变更快。这项工作确定了一个与设置谷氨酸转运率密切相关的区域。建议通过运输周期更快的过渡。这项工作确定了一个与设置谷氨酸转运率密切相关的区域。建议通过运输周期更快的过渡。这项工作确定了一个与设置谷氨酸转运率密切相关的区域。