Figure 5. Protection from MTS reagent inhibition by uridine.

Yeast producing recombinant hCNT3 mutants were incubated with MTS reagents as indicated in the presence (black bars) or absence (control; white bars) of 10 mM uridine for 5 min, washed three times with PBS and assayed for their ability to transport 1 μM [³H]uridine. Activity is expressed as the mean percentage of control value (no MTS reagent and no 10 mM uridine) for each individual mutant, with standard deviations of quadruplicate values from a representative experiment. Three independent experiments were performed and similar results were obtained.