Acts as a component of the essential kinetochore-associated NDC80 complex, which is required for chromosome segregation and spindle checkpoint activity (PubMed:12514103). Required for kinetochore integrity and the organization of stable microtubule binding sites in the outer plate of the kinetochore (By similarity). The NDC80 complex synergistically enhances the affinity of the SKA1 complex for microtubules and may allow the NDC80 complex to track depolymerizing microtubules (By similarity). Component of the NDC80 complex, which is composed of ndc80, cdca1, spbc24 and spbc25. The NDC80 complex interacts with mis12 and zwint. Localizes to kinetochores from late prophase to anaphase. Belongs to the NUF2 family.