Symporter that cotransports neutral amino acids and sodium ions from the extracellular to the intracellular side of the cell membrane (PubMed:10930503, PubMed:15774260, PubMed:15922329, PubMed:16621798). The transport is pH-sensitive, Li(+)-intolerant, electrogenic, driven by the Na(+) electrochemical gradient and cotransports of neutral amino acids and sodium ions with a stoichiometry of 1:1. May function in the transport of amino acids at the blood-brain barrier (PubMed:10930503, PubMed:15774260). May function in the transport of amino acids in the supply of maternal nutrients to the fetus through the placenta (By similarity). Maintains a key metabolic glutamine/glutamate balance underpinning retrograde signaling by dendritic release of the neurotransmitter glutamate (By similarity). Transports L-proline in differentiating osteoblasts for the efficient synthesis of proline-enriched proteins and provides proline essential for osteoblast differentiation and bone formation during bone development (By similarity).
