Features of Psh1 and Cse4 determine Cse4 stability. Histograms indicate intensity of Cse4. A. Strains with the genotype indicated (WT, psh1Δ, Psh1-RING, Psh1-ZINC) were transformed with a 2 micron plasmid containing Cse4 under control of the gal promoter. Cse4 was induced by exposure to galactose for 2 hours, cycloheximide was added, and cells were collected at the timepoints indicated for analysis by Western blotting using an anti-Cse4 antibody. 35 μg of total protein was loaded per lane. B. The stability of the Cse4-4K->A mutant was measured as in part A. The strain background in part A is W303 while the background in part B is S288C, which may account for the difference in Cse4 stability.