Shugoshin: a centromeric guardian senses tension.

To ensure accurate chromosome segregation during mitosis, the spindle checkpoint monitors chromosome alignment on the mitotic spindle. Indjeian and colleagues have investigated the precise role of the shugoshin 1 protein (Sgo1p) in this process in budding yeast. The Sgo proteins were originally identified as highly conserved proteins that protect cohesion at centromeres during the first meiotic division. Together with other recent findings, the study highlighted here has identified Sgo1 as a component that informs the mitotic spindle checkpoint when spindle tension is perturbed. This discovery has provided a molecular link between sister chromatid cohesion and tension-sensing at the kinetochore-microtubule interface.