Rnr1 levels are reduced in ixr1 after DNA damage.

(A) Western blot analysis of Rnr1 levels in wild-type (wt) (W1588-4C), ixr1-S366F (TOY734), and ixr1Δ (TOY736) strains before and after 2 hours treatment with 0.2 mg/L 4-NQO or 200 mM HU. (B) Quantification of Rnr1 levels in wild-type (wt) (W1588-4C), ixr1Δ (TOY736) and ixr1-S366F (TOY734) strains before and after 2 hours treatment with 0.2 mg/L 4-NQO or 200 mM HU. Tubulin was used as the internal control (see Materials and methods). Error bars represent standard error of the mean (SEM). (C) Lower panel, dynamics of Rnr1 decrease and Rnr4 increase in wt (W1588-4C, lanes marked with “w”) and ixr1Δ (TOY736, lanes marked with “i”) strains during a 12-hour time-course incubation with 0.2 mg/L 4-NQO. Upper panel, the corresponding flow-cytometric histograms. (D) Proliferation curves for the experiment in Figure 4C.