Figure 3. Drug susceptibility and transport assays of mutant variants of CaMDR1-GFP in S. cerevisiae.

Panel A: Drug resistance profile of wild type and mutant CaMDR1-GFP yeast strains determined by spot assay. For spot assay, cells were freshly streaked, grown overnight and then resuspended in normal saline to an A₆₀₀ of 0.1 (1×10⁶ cells) and 5 µl of five-fold serial dilutions, namely 1 (1∶5), 2 (1∶25), 3 (1∶125) and 4 (1∶625), of each strain was spotted on to YEPD plates in the absence (control) and presence of the following drugs: FLU (0.20 µg/ml), CYH (0.20 µg/ml), 4-NQO (0.20 µg/ml) and MTX (65 µg/ml). Growth differences were recorded following incubation of the plates for 48 hrs at 30°C. Growth was not affected by the presence of the solvents used for the drugs (data not shown). B: [³H] MTX and [³H] FLU accumulation in the different mutant variants of CaMdr1p-GFP. Controls AD1-8u⁻ and RPCaMDR1-GFP have also been included for comparison. The results are means±standard deviations for three independent experiments.