b(0,+)-type amino acid transporter 1 (b(0,+)AT1)

System b0,+ amino acid transporter (b(0,+)-type amino acid transporter 1; SLC7A9) is a heteromeric membrane transporter comprising a polytopic light chain (SLC7A9) and a single-transmembrane heavy chain partner (typically rBAT/SLC3A1). It mediates sodium-independent, electrogenic exchange between cationic amino acids (such as lysine and arginine), neutral amino acids, and cystine mainly in the brush border of renal and intestinal epithelial cells. The transporter is essential for reabsorption of filtered cystine and dibasic amino acids from the urine; mutations lead to cystinuria, a hereditary disorder characterized by kidney stones. Its structure includes a LeuT fold and alternating access mechanism for substrate binding and translocation. In cancer, the transporter may be upregulated to support increased amino acid demand and is considered a potential therapeutic target. System b0,+ is distinct from other SLC family amino acid transporters in substrate specificity, structure, and physiological role.

Other names

SLC7A9b(0,+)ATBAT1System b(0,+)b(0,+) amino acid transporterdibasic and neutral amino acid transporterAssociated complex: rBAT (SLC3A1)

Competitive inhibition of amino acid transport (blocking substrate recognition or translocation); Interference with antiporter exchange cycles; Alteration of cell amino acid pools and viability in disease or cancer context.