Functions as a permease involved in the transport of the cationic amino acids (L-arginine, L-lysine, L-ornithine and L-homoarginine); the affinity for its substrates differs between isoforms created by alternative splicing (PubMed:28684763, PubMed:9174363). May play a role in classical or alternative activation of macrophages via its role in arginine transport (By similarity). ; [Isoform 1]: Functions as a permease that mediates the transport of the cationic amino acids (L-arginine, L-lysine, L-ornithine and L-homoarginine). Shows a much higher affinity for L-arginine and L-homoarginine than isoform 2. ; [Isoform 2]: Functions as a low-affinity, high capacity permease involved in the transport of the cationic amino acids (L-arginine, L-lysine, L-ornithine and L-homoarginine).
