Uptake of the purines adenine and guanine, and the pyrimidine uracil. Transport is probably proton-dependent. Inhibited by the proton gradient disruptor carbonyl cyanide m-chlorophenylhydrazone (CCCP), but not by the sodium gradient disruptor ouabain. Hypoxanthine, xanthine, cytosine and uric acid act as competitive inhibitors. Belongs to the nucleobase:cation symporter-2 (NCS2) (TC 2.A.40) family.