Acts as a component of the essential kinetochore-associated NDC80 complex, which is required for chromosome segregation in mitosis and meiosis and spindle checkpoint activity (PubMed:11402066, PubMed:14522947, PubMed:15371539). The ndc-80 complex synergistically enhances the affinity of the ska-1 complex for microtubules and may allow the ndc-80 complex to track depolymerizing microtubules (PubMed:23085020). Component of the NDC80 complex, which is composed of at least ndc-80 and him-10. The NDC80 complex interacts with knl-1. Localizes to kinetochores. Belongs to the NUF2 family.