SLC6A15 belongs to the solute carrier 6 (SLC6) gene family which also includes the monoamine and gamma-amino butyric acid (GABA) transporters and codes for a sodium-dependent branched-chain amino acid transporter (Broer, 2006). Experimental data from SLC6A15 knockout mice indicate a moderate contribution of SLC6A15 to total proline and leucine transport into cortical synaptosomes of about 15% (Dronova et al., 2007). Proline, the amino acid with the highest affinity for SLC6A15, and leucine may act as precursors for glutamate synthesis (Broer et al., 2006) and this transporter could thus be involved in the regulation of glutamate transmission (Tapiero et al., 2002).
