Acts as a component of the essential kinetochore-associated NDC80 complex, which is involved in chromosome segregation and spindle checkpoint activity. Component of the NDC80 complex, which consists of NDC80, NUF2, SPC24 and SPC25. The NDC80 complex is formed by two subcomplexes, NDC80-NUF2 and SPC24-SPC25, which are joined end-to-end through their coiled-coil domains. It has a rod-like structure with a length of 570 Angstroms and globular domains at either end. The NDC80-NUF2 globular domains are probably directed to microtubules, the SPC24-SPC25 globular domains to the centromere. NDC80 probably interacts with SMC1 and SMC2. Also interacts with KIN3. Interacts with DMC1. Associated with kinetochores. Present with 1160 molecules/cell in log phase SD medium. Belongs to the NDC80/HEC1 family.