Putative sodium-dependent amino acid/proton antiporter. Expressed in fetal and adult brain, and spinal cord. In the brain, it is localized in the cell body and axon of the majority of neuronal cells and in a subset of glial cells. Found throughout the neuronal retina, with higher expression levels in the inner and outer plexiform layers and the photoreceptor layer. Very weak expression is also present in the kidneys, thymus, and testes. The disease is caused by variants affecting the gene represented in this entry. Belongs to the amino acid/polyamine transporter 2 family.