FIG. 5.

(A) 4-NQO treatment of the Gal-RSP5 strain maintained in galactose or shifted to dextrose. The Gal-RSP5 strain was grown to early log phase in galactose-containing medium, and then the cells were either shifted to dextrose-containing medium for 48 h or maintained in galactose-containing medium. The cultures were then treated with 4-NQO at the indicated concentrations for 30 min, and whole-cell extracts were prepared and analyzed by SDS-PAGE and immunoblotting with either an anti-Rsp5 monoclonal antibody (bottom) or anti-CTD antibody (top). (B) 4-NQO treatment of the rsp5-1 temperature-sensitive mutant. Strains FY56 (RSP5) and FW1808 (rsp5-1) were grown to mid-log phase at 30°C and then shifted to 37°C for 1 h. 4-NQO was then added at the indicated concentrations for 30 min. Whole-cell extracts were prepared, and Rpb1 was detected by SDS-PAGE and immunoblotting. (C) Experiment similar to that in panel B, except that cells were treated with 4-NQO at both 30 and 37°C.