Transports natural purines (adenine and guanine) as well as purine analogs. Confers sensitivity to 8-azaadenine and 8-azaguanine (8-azg). Resistance to 8-azaadenine and 8-azaguanine, and, to a lower extent, to 5-fluorouracil, but not to other toxic nucleobase analogs. Deficiency in the uptake of adenine and guanine. Belongs to the nucleobase:cation symporter-2 (NCS2) (TC 2.A.40) family. Azg-like subfamily.