FIGURE 5.

The wtAhR and select AhR mutants demonstrate similar sensitivity to geldanamycin. COS-1 cells were transiently transfected with the indicated AhR constructs (the wtAhR or 3M AhR (F279T/I280E/R282I)) under conditions similar to the co-immunoprecipitation experiments, cells were incubated with 0.1 μm geldanamycin (or 0.1% (v/v) DMSO) for the indicated times, and AhR levels in cell lysates were determined by Western blot assay. A, representative gels are shown, and protein quantitation of duplicate samples is presented in the graph. Values represent the mean of two reactions, and error bars indicate the range of the results. B, geldanamycin-induced decrease in AhR levels is statistically significant and similar among AhR constructs. Geldanamycin-dependent AhR protein degradation after a 4-h incubation was measured as described for A, and the values are expressed as the means ± S.D. of three independent reactions. Values significantly different from the corresponding DMSO reaction values at p < 0.05 as determined by the Student's t test are indicated (*).