Figure 3.
APC/CCdc20 mediated destruction of Ume6 is required for meiotic entry. Under rich growing conditions, PKA phosphorylation inhibits Cdc20 activity both protecting destruction of Ume6 is required for meiotic entry and preventing transcription of the meiotic inducer IME1 (left panel). Switching cultures to medium lacking a fermentable carbon source but containing nitrogen reduces PKA activity which permits partial Ume6 destruction (middle panel). Removing nitrogen allows Ime1 production which, along with fully active Cdc20, completely destroys Ume6 allowing early meiotic gene (EMG) induction and meiotic progression (right panel).