Fig. 7. Relationship between Clb2 and Wee1. (A) Epistatic analysis of clb2 and wee1. The single mutant TAU42 (clb2^nar) and UMC23 (wee1^nar) strains, and the double mutant strain UMP40 (clb2^{na r} wee1^nar) were grown in restrictive conditions (YPD) for 8 hours. Note that the phenotype of the double mutant in these conditions is similar to the phenotype of the clb2^nar cells. Scale bars: 20 µm. (B) Overexpression of wee1 overcomes the morphological effects imposed by high levels of Clb2. UMC45 cells that express constitutively high levels of clb2 and carry the ectopic arabinose-inducible P_crg:wee1 allele, grow as filaments with short cell compartments in non-inducing conditions (YPD). Transferring the same cells to inducing conditions (YPA) produces elongated cells that resemble wild-type cells overexpressing wee1. Scale bars: 20 µm). (C) Inhibitory phosphorylation of B cyclin-associated Cdk1. Protein extracts from cells expressing epitope-tagged versions of Cln1 (SONU58), Clb1 (UMP19) and Clb2 (UMP27) were immunoprecipitated with anti-myc (Cln1 and Clb2 extracts) or anti-VSV (Clb1 extract). Whole cell extracts (WCE) and immunoprecipitates (IP) were immunoblotted with anti-phospho-Cdc2 (Tyr15) and anti-PSTAIRE antibodies. Cdk2 is the U. maydis homolog of S. cerevisiae Pho85, which is also recognized by the anti-PSTAIRE antibody.