Fig. 3.

Inhibition of [³H]uridine uptake into PbENT1-HA–expressing yeast by various purine nucleosides and nucleobases. (A–D) Uptake inhibition of 250 nM [³H]uridine into PbENT1-HA– expressing yeast by adenosine, adenine (A); inosine, hypoxanthine (B); guanosine, guanine (C); and xanthosine, xanthine (D). Uptake is normalized to remove background and is shown as the percentage of maximum uptake. All tested substrates fully inhibited [³H]uridine uptake, with the exception of the nucleobases xanthine and guanine and the nucleoside xanthosine. IC₅₀ values are shown in Table 1. Data from a representative experiment are shown.