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