Figure 2.

LIF2 is required for the religation of an HO cut at MAT in the absence of a homologous sequence. Yeast strains Lev348 (WT), Lev406 (lif2Δ), Lev349 (dnl4Δ), and Lev379 (lif1Δ) grown exponentially in raffinose-containing medium were blocked in late G₁ phase by the addition of α factor (Sigma, 60 ng/ml) for 4 h and exposed to galactose for an additional 1 h. Cells were resuspended in glucose-containing medium and maintained in G₁ phase with α factor for an additional 4 h. Genomic DNAs were digested with EcoRV, separated by electrophoresis on a 1% agarose gel, and blotted onto a nitrocellulose membrane. The membrane was probed with a 700-bp fragment immediately adjacent to the HO site. After exposure, the membrane was rehybridized with a TRP1 fragment (data not shown). The signal from the uncut/repaired MAT band at 5.5 kb was quantified with Image-Quant using the signal at TRP1 as an internal control for each lane and normalized for each strain.