Figure 3.

rum1p binds to and inhibits the cdc13p–cdc2p kinase in P-factor. (A) cig2p- and cdc13p-associated H1 kinase activities in a rum1Δcyr1Δsxa2Δ after exposure to P-factor at 25°C. (B) Immunoprecipitations from a rum1-HAcyr1Δsxa2Δ strain with anti-cdc13p and anti-cig2p antibodies before and 3 h after P-factor addition, Western blotted, and probed with anti-HA-antibody. (C) Immunoprecipitations from a rum1-HAcyr1Δsxa2Δ strain with anti-HA antibodies 3 h after P-factor addition, Western blotted, and probed with antibodies raised against cig2p (left panel) and cdc13p (right panel). Extracts (2 and 5 μl) containing the indicated amounts of cig2p and cdc13p were loaded to quantify the coimmunoprecipitated cyclins. (D) FACS analysis of h⁻rum1Δcyr1Δsxa2Δ, h⁻cig2Δrum1Δcyr1Δsxa2Δ mutants incubated in P-factor for 6 h at 25°C.