Fig. 7. Nuclear export of Cdh1p may contribute to the inactivation of APC/CCdh1. Model for the inactivation of APC/CCdh1 after bud emergence. Phosphorylation of Cdh1p by Cdk1 (predominantly Cdc28p–Clb5p) prevents its interaction with the APC/C core complex (Zachariae et al., 1998), and promotes nuclear export by Msn5p. Cytoplasmic sequestration of Cdh1p prevents the assembly of functional APC/CCdh1 complexes during cell cycle stages other than G1, thereby contributing to the inactivation of APC/CCdh1.