The SLC7A7 gene encodes a protein of 511 amino acids called y+L amino acid transporter 1 (y+LAT-1). This protein is involved in transporting lysine, arginine, and ornithine from the small intestines and kidneys to the rest of the body. The y+LAT-1 protein is the light subunit of the heterodimeric cationic amino acid transporter. This subunit is responsible for binding to the amino acids that are transported. It also plays a role in nitric oxide synthesis in human umbilical vein endothelial cells (HUVECs) via transport of L-arginine.
Defects in the y(+)LAT1 protein cause lysinuric protein intolerance (LPI), which is characterized by increased renal excretion of cationic amino acid (CAA), reduced CAA absorption from intestine, and orotic aciduria.