Uniporter that mediates the uptake of cationic L-amino acids such as L-arginine, L-lysine and L-ornithine (PubMed:11591158). The transport is sodium ions- and pH-independent, moderately trans- stimulated and is mediated by passive diffusion (PubMed:11591158). . This is the function of SLC7A3 (solute carrier family 7 member 3, Ensembl gene identifier ENSG00000165349).