FIG. 3.

DNA-damage-dependent activation of RNR3 transcription and Rad53 is normal in yng2 mutants. A hallmark of the DNA damage response is transcriptional activation of DNA damage genes, such as RNR3, and phosphorylation of the checkpoint protein Rad53. Asynchronously growing wild-type (YNG2) and yng2 mutant cells treated with 0.03% MMS were collected at the indicated times. Cells were processed for Northern analysis (A) to detect RNR3 expression and for Western analysis (B) to examine Rad53. Both wild-type and yng2 mutant cells induce RNR3 expression in the presence of MMS. Similarly, YNG2 and yng2 mutant cells expressing Rad53-Myc accumulate shifted forms (consistent with phosphorylation) of Rad53-Myc to similar levels when treated with MMS. Note the appearance of RNR3 transcript in yng2 mutants (A) even in the absence of MMS treatment (0-h lane).