Sodium-dependent, high-affinity amino acid transporter that mediates the uptake of L-glutamate and also L-aspartate and D-aspartate (PubMed:7903437, PubMed:28032905). Functions as a symporter that transports one amino acid molecule together with two or three Na(+) ions and one proton, in parallel with the counter-transport of one K(+) ion (By similarity). Plays a redundant role in the rapid removal of released glutamate from the synaptic cleft, which is essential for terminating the postsynaptic action of glutamate (PubMed:15363892, PubMed:15390100,PubMed:16880397). H(+)(out) + K(+)(in) + L-glutamate(out) + 3 Na(+)(out) = H(+)(in) + K(+)(out) + L-glutamate(in) + 3 Na(+)(in) H(+)(out) + K(+)(in) + L-aspartate(out) + 3 Na(+)(out) = H(+)(in) + K(+)(out) + L-aspartate(in) + 3 Na(+)(in) D-aspartate(out) + H(+)(out) + K(+)(in) + 3 Na(+)(out) = D-aspartate(in) + H(+)(in) + K(+)(out) + 3 Na(+)(in) Homotrimer (By similarity). Detected in brain, in Bergmann glia arborising into the molecular layer of the cerebellum (at protein level) (PubMed:15363892). Localized in brain and is highly enriched in the Purkinje cell layer in cerebellum. Intermediate level in lung, low level in spleen, skeletal muscle and testis. Contains eight transmembrane regions plus two helical hairpins that dip into the membrane. These helical hairpin structures play an important role in the transport process. The first enters the membrane from the cytoplasmic side, the second one from the extracellular side. During the transport cycle, the regions involved in amino acid transport, and especially the helical hairpins, move vertically by about 15-18 Angstroms, alternating between exposure to the aqueous phase and reinsertion in the lipid bilayer. In contrast, the regions involved in trimerization do not move. Glycosylated. No visible phenotype (PubMed:15363892, PubMed:15390100). Mutant mice display normal locomotion, motor coordination and learning, and globally normal glutamate uptake in brain vesicle preparations (PubMed:15363892). The decay time of glutamate receptor mediated excitatory postsynaptic currents (EPSCs) in cerebellar Purkinje is slightly increased (PubMed:15363892). The decreased rate of glutamate uptake in retina Mueller cells from mutant mice suggests that Slc1a3 accounts for about half of the glutamate uptake activity in wild-type cells (PubMed:15390100). Mice deficient in both Slc1a2 and Slc1a3 die at about 17 dpc (PubMed:16880397). Belongs to the dicarboxylate/amino acid:cation symporter (DAACS) (TC 2.A.23) family. SLC1A3 subfamily.