Fig. 4.

Phosphorylation within two Cdc4 phospho-degrons controls Hst3 turnover. Hst3 was expressed under the control of the GAL1 promoter. Expression was induced by the addition of galactose, and turnover was followed for 45 min after the addition of cycloheximide, with time points taken every 15 min. For turnover in 0.2 M HU, cells were grown in galactose for 2.5 h; then 0.2 M HU was added for an additional 2.5 h (still in the presence of galactose), and cells were treated with cycloheximide. (A–F) Site mutants were used as designated, with wild-type phosphorylated residues in red and mutations in black for each degron (D1 and D2). All gels are quantified in Fig. S3.