FIGURE 3.

Oxidation of the Cys-404 residue to sulfenic acid in LoaOOH-treated cells. A, detection of sulfenic acid in Swi6p in LoaOOH-treated cells. The cells were exposed to LoaOOH (30 μm, 5 min) and were subsequently treated with dimedone as under “Experimental Procedures.” The cells were lysed, and Swi6p or C404Ap was immunoprecipitated (IP) from cell extracts and subjected to immunoblotting (IB) for the presence of sulfenic acid. B, time course of sulfenic acid formation in Swi6p in a synchronous population on LoaOOH treatment and post release from treatment. The cells were arrested at G₁ using α-factor, washed, and resuspended in PBS followed by treatment with 30 μm LoaOOH. The samples were taken at the indicated time intervals and treated with dimedone. Additionally LoaOOH-treated cells were washed and released in fresh medium to initiate cell division, and the samples were taken again at intervals as indicated. The cell extracts were prepared, and Swi6p was immunoprecipitated for detection of sulfenic acid as described above.