Functions as a sodium-dependent amino acid transporter which countertransport protons. Mediates the saturable, pH-sensitive, and electrogenic cotransport of several neutral amino acids including glycine, asparagine, alanine, serine, glutamine and histidine with sodium. Not inhibited by lithium. Highly expressed in neocortex, hippocampus, striatum and spinal cord by astrocytes (at protein level). Expressed in brain, lung, stomach, liver, kidney, spleen and testis. Belongs to the amino acid/polyamine transporter 2 family.