InterPro domain: IPR034586

Bfa1 is required for the spindle assembly checkpoint in budding yeast. It functions in the same pathway with Bub2 in one of the branches of the spindle assembly checkpoint which prevents cytokinesis before the completion of chromosome segregation [ 1 , 2 ]. Bub2 and Bfa1 are also required for the maintenance of G2/M arrest in response to DNA damage and to spindle misorientation [ 3 ]. The homologue of Bfa1 in fission yeast is Byr4, which together with Cdc16 (homologue of Bub2) forms a two-component GTPase-activating protein for Spg1 GTPase [ 4 , 5 ]. Spg1 GTPase positively regulates septation and constriction of the actomyosin ring for cell division.

Bfa1 and Bub2 may function as a universal checkpoint in response to various checkpoint signals to avoid improper mitotic exit [ 6 ].

1. Bifurcation of the mitotic checkpoint pathway in budding yeast. Proc. Natl. Acad. Sci. U.S.A. 96, 4989-94
2. A Bub2p-dependent spindle checkpoint pathway regulates the Dbf2p kinase in budding yeast. EMBO J. 18, 2424-34
3. The Bfa1/Bub2 GAP complex comprises a universal checkpoint required to prevent mitotic exit. Curr. Biol. 10, 1379-82
4. Byr4 and Cdc16 form a two-component GTPase-activating protein for the Spg1 GTPase that controls septation in fission yeast. Curr. Biol. 8, 947-54
5. Regions of Byr4, a regulator of septation in fission yeast, that bind Spg1 or Cdc16 and form a two-component GTPase-activating protein with Cdc16. J. Biol. Chem. 274, 11339-43
6. The C-terminus of Bfa1p in budding yeast is essential to induce mitotic arrest in response to diverse checkpoint-activating signals. Genes Cells 9, 399-418