Regulation of the localization of Dbf2 and Mob1 during cell division of Saccharomyces cerevisiae

The mitotic exit network (MEN) governs Cdk inactivation. In budding yeast, MEN consists of the protein phosphatase Cdc14, the ras-like GTPase Tem1, protein kinases Cdc15, Cdc5, Dbf2 and Dbf2-binding protein Mob1. Tem1, Dbf2, Cdc5 and Cdc15 have been reported to be localized at the spindle pole body (SPB). Here we report changes of the localization of Dbf2 and Mob1 during cell division. Dbf2 and Mob1 localize to the SPBs in anaphase and then moves to the bud neck, just prior to actin ring assembly, consistent with their role in cytokinesis. The neck localization, but not SPB localization, of Dbf2 was inhibited by the Bub2 spindle checkpoint. Cdc14 is the downstream target of Dbf2 in Cdk inactivation, but we found that the neck localization of Dbf2 and Mob1 was dependent on the Cdc14 activity, suggesting that Dbf2 and Mob1 function in cytokinesis at the end of the mitotic signaling cascade.