Sodium Coupled Neutral Amino Acid Transporter 2 (SNAT2)

The amino acid transport system A, named for its preference for alanine as substrate, is known to be present in most mammalian tissues. The characteristics of system A include sodium dependence, preference for short-chain neutral amino acids, such as alanine, serine, proline, and glutamine, as substrates, pH sensitivity, and transinhibition. Bulky hydrophobic amino acids, anionic amino acids, and cationic amino acids are excluded by the system. However, system A can be discriminated from other known transport systems for neutral amino acids by its unique ability to transport N-methylated amino acids. System A is defined as the component of sodium-dependent transport of any neutral amino acid that is inhibitable by the model substrate alpha-(methylamino)isobutyric acid (MeAIB).