Symporter that cotransports neutral amino acids and sodium ions, coupled to an H(+) antiporter activity (PubMed:11243884). Releases L-glutamine and glycine from astroglial cells and may participate in the glutamate/GABA-L-glutamine cycle and the NMDA receptors activation (By similarity). In addition, contributes significantly to L-glutamine uptake in retina, namely in ganglion and Mueller cells therefore, participates in the retinal glutamate-glutamine cycle (By similarity). The transport activity is pH sensitive and Li(+) tolerant (PubMed:11243884). Moreover functions in both direction and is associated with large uncoupled fluxes of protons (By similarity). The transport is electroneutral coupled to the cotransport of 1 Na(+) and the antiport of 1 H(+) (By similarity). May have a particular importance for modulation of net hepatic glutamine flux (By similarity).