Sodium-independent purine-selective nucleobase transporter which mediates the equilibrative transport of extracellular purine nucleobases such as adenine, guanine and hypoxanthine (PubMed:26455426, PubMed:32339528). May regulate fatty acid (FA) transport in adipocytes, acting as a positive regulator of FA efflux and as a negative regulator of FA uptake (By similarity). {ECO:0000250|UniProtKB:A2AVZ9, ECO:0000269|PubMed:26455426, ECO:0000269|PubMed:32339528}. [Isoform 1]: Sodium-independent purine-selective nucleobase transporter which mediates the equilibrative transport of extracellular purine nucleobase adenine (PubMed:30910793). Mediates the influx and efflux of the purine nucleobase analog drug 6-mercaptopurine across the membrane (PubMed:30910793). . [Isoform 2]: Sodium-independent purine-selective nucleobase transporter which mediates the equilibrative transport of extracellular purine nucleobase adenine (PubMed:30910793). Mediates the influx and efflux of the purine nucleobase analog drug 6-mercaptopurine across the membrane (PubMed:30910793). . This is the function of ENSG00000134802 (SLC43A3, solute carrier family 43 member 3).