Without its GAP activity, Bub2 (white) remains on both SPBs and blocks mitotic exit.

To prevent chromosome segregation errors, cytokinesis in Saccharomyces cerevisiae awaits the arrival of a spindle pole body (SPB) in the bud. On page 335, Fraschini et al. show that this arrival is announced by the mother-bound SPB, which heralds the onset of cytokinesis and mitotic exit.

Mitotic exit relies on a G-protein called Tem1, which activates the destruction of mitotic cyclins.

As Tem1 is activated by Lte1, which is found in the bud, Tem1's arrival in the bud on the SPB was thought to trigger timely mitotic exit. But another mechanism for Tem1 activation is revealed in the new study, thus partly explaining why Lte1 is not essential.

Whereas Lte1 activates Tem1, a SPB-localized complex of Bub2 and Bfa1 is known to keep Tem1 inactive during spindle assembly and orientation....

The Rockefeller University Press
2006
The Rockefeller University Press
2006
You do not currently have access to this content.