FIGURE 5: Importance of Mms1 and Rtt105 on CEB1 stability. (A) Mms1 is not required to stabilize CEB1. Left, genomic DNAs from mms1Δ yeast cells bearing the leading-CEB1 were digested by ApaI and XhoI and southern blotted. Right, genomic DNAs from mms1Δ yeast cells bearing the lagging-CEB1 were digested by ApaI and NcoI and southern blotted. Membranes were hybridized with the CEB1-0.6 probe. (B) Rtt105 is required to stabilize both leading-CEB1 and lagging-CEB1. Left, genomic DNAs from rtt105Δ yeast cells bearing the leading-CEB1 were digested by ApaI and XhoI and southern blotted. Right, genomic DNAs from rtt105Δ yeast cells bearing the lagging-CEB1 were digested by ApaI and NcoI and southern blotted. Membranes were hybridized with the CEB1-0.6 probe. WT: wild-type genomic DNA. The arrows show the position of stable leading-CEB1 (left) and stable lagging-CEB1 (right). The horizontal dashed lines indicate the theoretical position of stable CEB1. M: ladder DNA serving as size standard (kbp). The number of colonies analysed per well, the percentage of rearrangement frequencies, and the total numbers of colonies are indicated in Table 1.