FIG. 5.

Fluorescein maleimide reactivities of mutants containing cysteine substitutions at W58A suppressor positions in disrupted cell membranes (A) and whole cells (B). Fluorescein maleimide-treated QacA mutant proteins were purified and fractionated on SDS-polyacrylamide gels. (Top panels) Total QacA protein levels determined by Coomassie blue staining (A) or Western blotting with an anti-QacA antiserum (B). (Lower panels) Fluorescein maleimide label associated with mutant QacA proteins. The relative levels of fluorescein maleimide labeling as percentages of the labeling of the previously characterized QacA P309C mutant (32) are given below the gels and are averages from two repeat experiments.