In budding yeast, the Start checkpoint in the G1 cell cycle phase is a point after which cells are irreversibly committed to cell division. Previous work has identified a linear pathway that triggers the Start transition. In contrast, analyses of single cells reveal that Start represents a positive feedback-dependent sharp switch that coordinates the simultaneous transcription of a large group of cell cycle genes and the budding of a daughter cell.
- Jan M. Skotheim
- Stefano Di Talia
- Frederick R. Cross