This protein involved in the sodium-independent uptake of dibasic amino acids and sodium-dependent uptake of some neutral amino acids. It requires co-expression with SLC3A2/4F2hc to mediate the uptake of arginine, leucine and glutamine. It also acts as an arginine/glutamine exchanger, following an antiport mechanism for amino acid transport, influencing arginine release in exchange for extracellular amino acids. It plays a role in nitric oxide synthesis in human umbilical vein endothelial cells (HUVECs) via transport of L-arginine. It involved in the transport of L-arginine in monocytes and reduces uptake of ornithine in retinal pigment epithelial (RPE) cells.

2-8°C (short-term); -20°C (long-term)