FIG. 3.

Cdc2p phospho-Tyr15 levels continue to cycle in the APC cut mutants. Wild-type (A), lid1-6 (B), and cut9-665 (C) cells were grown to mid-log phase at 25°C in YE medium, synchronized in early G₂ by centrifugal elutriation, filtered, and then released into prewarmed medium at 36°C. The cells were collected at 15-min (for wild-type cells) or 20-min (for APC mutants) intervals, and the septation index and percentage of cut cells were determined in each sample. Protein lysates were also prepared from each sample. Cdc2p levels and the Cdc2p-Tyr15 phosphorylation state were determined by immunoblotting using PSTAIR monoclonal and phospho-Cdc2 (Tyr15) polyclonal antibodies, respectively. anti-PTyr, antiphosphotyrosine.