Related Experiment Video
Updated: Jun 11, 2026

Studying Cell Cycle-regulated Gene Expression by Two Complementary Cell Synchronization Protocols
Published on: June 6, 2017
Regulation of the Bub2/Bfa1 GAP complex by Cdc5 and cell cycle checkpoints
1Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
Abstract:
During mitosis, a ras-related GTPase (Tem1) binds GTP and activates a signal transduction pathway to allow mitotic exit. During most of the cell cycle, Tem1 function is antagonized by a GTPase-activating protein complex, Bfa1/Bub2. How the Bfa1/Bub2 complex is regulated is not well understood. We find that Polo/Cdc5 kinase acts upstream of Bfa1/Bub2 in the mitotic exit network. Cdc5 phosphorylates Bfa1 and acts to antagonize Bfa1 function to promote mitotic exit. Bfa1 is regulated by multiple cell cycle checkpoints. The spindle assembly and spindle orientation checkpoints inhibit Bfa1 phosphorylation. DNA damage does not inhibit Bfa1 phosphorylation and instead causes a Rad53- and Dun1-dependent modification of Bfa1. Regulation of Bfa1 may therefore be a key step controlled by multiple checkpoint pathways to ensure a mitotic arrest.
Related Concept Videos
Negative Regulator Molecules
The Cell Cycle Control System
Inhibition of Cdk Activity
The Cell Cycle Control System
The Cell Cycle Control System
Cyclins and cyclin-dependent kinases (Cdks) are the primary cell cycle regulators and function at the cell...
Molecular Factors Affecting Cell Division
Several proteins function as internal regulators to ensure each cell cycle stage is completed faithfully before proceeding to the next. Regulator molecules may act directly or influence the activity or production of other...

