Figure 1

The Ndc80 internal loop plays distinct roles in kinetochore-microtubule attachment by recruiting multiple regulatory factors to the outer kinetochore. In budding yeast, the Ndc80 loop helps to recruit the Dam1 complex to the outer kinetochore (left); whilst in fission yeast, the Ndc80 loop binds to and recruits the Dis1/TOG and Alp7/TACC-Alp14/TOG complexes (centre). In higher eukaryotes, the Ndc80 loop has been shown to be able to recruit the Cdt1 protein and the Ska complex, either directly or indirectly (right). Note that no microtubule-binding activity has been reported for the Cdt1 protein (depicted by ?). We suggest that the Ndc80 loop plays a role in protein-protein interaction to ensure proper kinetochore-microtubule attachment.