SLC7A7 encodes y+LAT-1, the catalytic light chain of a heterodimeric amino acid transporter that functions with SLC3A2 (4F2hc) to mediate cationic amino acid transport 1. The transporter operates as an electroneutral antiporter, exchanging intracellular cationic amino acids (particularly L-arginine and lysine) for extracellular neutral amino acids and sodium ions 1. This mechanism is essential for arginine availability, supporting nitric oxide synthesis and monocyte/macrophage function 2. Beyond canonical transport, SLC7A7 exerts anti-inflammatory effects, acting as a physiological brake on inflammatory signaling through NFκB-dependent pathways in macrophages and epithelial cells 2. Recent evidence reveals SLC7A7's role in metabolic reprogramming: it mediates glutamine influx in atherosclerotic macrophages, enabling GLS1-dependent glutaminolysis required for restorative immune functions and plaque stability 3. In hepatocellular carcinoma, ATF3-driven SLC7A7 expression suppresses mTORC1 signaling and lipogenesis, implicating SLC7A7 in tumor suppression 4. Clinically, biallelic SLC7A7 mutations cause lysinuric protein intolerance (LPI), a rare inherited aminoaciduria presenting with protein malabsorption, hyperammonemia, and complications including hepatosplenomegaly, neurological impairment, and immune dysfunction 1 5. Expert consensus supports SLC7A7-LPI screening in newborn genome sequencing for early therapeutic intervention 6.