Acts as a component of the essential kinetochore-associated NDC80 complex, which is required for chromosome segregation and spindle checkpoint activity (PubMed:12829748). 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 at least NDC80/HEC1 and CDCA1. Localizes to kinetochores from late prophase to anaphase and to the centrosome during G1 and S phase. Belongs to the NUF2 family.