SLC7A13 (solute carrier family 7 member 13), also known as AGT1, encodes a light-chain subunit that associates with SLC3A1/rBAT to form a functional heterodimeric cystine transporter 1. This complex mediates exchange transport of anionic and neutral amino acids, particularly L-cystine, across the apical plasma membrane of renal epithelial cells in the S3 segment (late proximal tubules), exchanging luminal cystine for cytosolic glutamate or aspartate 1. While initially proposed as a cystinuria candidate gene, SLC7A13 mutations do not appear to be causative in most patients without SLC3A1/SLC7A9 mutations 23, though potential modulatory roles remain unexplored 3. Beyond renal physiology, SLC7A13 has emerged as clinically significant in cancer biology. Gene amplification and overexpression occur in ~20-50% of breast cancers and associate with worse survival in luminal subtypes 4. SLC7A13 overexpression promotes cystine uptake and glutathione biosynthesis, reducing oxidative stress and ferroptosis-induced cell death 4. The cryo-EM structure reveals a dimer-of-heterodimers architecture with a substrate-binding pocket suitable for therapeutic targeting 4. SLC7A13 is also identified as part of differentially expressed gene networks in polycystic kidney disease and represents a therapeutic target in hepatocellular carcinoma via ferroptosis induction 56.