SLC6A15 (solute carrier family 6 member 15) is a sodium-dependent neutral amino acid transporter that mediates saturable, pH-sensitive cotransport of branched-chain amino acids (leucine, valine, isoleucine) and other neutral amino acids including methionine, alanine, phenylalanine, and proline 1. Unlike other neurotransmitter transporters, SLC6A15 operates independently of chloride ions. The transporter functions across multiple organ systems including the central nervous system, kidneys, and intestines, where it facilitates amino acid absorption and supplies neurotransmitter precursors to neurons 1. In the blood-brain barrier, SLC6A15 (designated B0AT2) cooperates with LAT1 and other transporters to mediate L-leucine uptake 2. Disease relevance encompasses psychiatric and metabolic conditions. Altered SLC6A15 expression associates with depression and stress-related disorders 1, with genetic polymorphisms affecting resting-state brain function in major depressive disorder patients, particularly in the corpus callosum and cingulum 3. SLC6A15 acts as a tumor suppressor in papillary thyroid cancer, where downregulation correlates with metastatic potential 4. The transporter also regulates melanogenesis through phenylalanine transport, with UVB exposure upregulating SLC6A15 to enhance pigmentation 5. Additionally, SLC6A15 gene variants associate with insulin resistance in metabolic syndrome 6, and reduced expression occurs in lymphedema-associated adipose tissue 7. Therapeutically, SLC6A15 inhibition shows promise for psychiatric disorder treatment 1.