Sodium-dependent, high-affinity amino acid transporter that mediates aspartate uptake (PubMed:17435767, PubMed:19380583, PubMed:17230192, Ref.11). Has only very low glutamate transport activity (PubMed:19380583, PubMed:17230192). Functions as a symporter that transports one amino acid molecule together with two or three Na(+) ions, resulting in electrogenic transport (PubMed:17435767, PubMed:19380583, Ref.11). Na(+) binding enhances the affinity for aspartate (PubMed:19380583, Ref.11). Mediates Cl(-) flux that is not coupled to amino acid transport; this avoids the accumulation of negative charges due to aspartate and Na(+) symport (PubMed:17435767). In contrast to mammalian homologs, transport does not depend on pH or K(+) ions (PubMed:19380583). Homotrimer. 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, regions involved in trimerization do not move. Belongs to the dicarboxylate/amino acid:cation symporter (DAACS) (TC 2.A.23) family.