Associates with SLC3A2/4F2hc to form a functional heterodimeric complex that translocates small neutral L- and D-amino acids across the plasma membrane. Preferentially mediates exchange transport, but can also operate via facilitated diffusion (By similarity) . Acts as a major transporter for glycine, L- and D-serine in the central nervous system. At the spinal cord and brainstem regulates glycine metabolism and glycinergic inhibitory neurotransmission by providing for glycine de novo synthesis from L-serine and glycine recycling from astrocytes to glycinergic motor neurons (By similarity). At Schaffer collateral-CA1 synapses mediates D-serine and glycine release that modulates post-synaptic activation of NMDA receptors and excitatory glutamatergic transmission (By similarity). May regulate D-serine release from mesenchymal progenitors located in developing subcutaneous adipose tissue, favoring white adipocyte over thermogenic beige adipocyte lineage commitment (By similarity).
Subcellular locations: Cell membrane
Colocalizes with OLIG2 in astrocytic processes. Localizes to the plasma membrane in mature adipocytes and to intracellular structures in preadipocytes.
Expressed in brain, heart, kidney, liver, lung, pancreas, placenta, and skeletal muscle.