Required for accurate chromosome segregation. Excluded from the nucleus during interphase but migrates into the nuclear zone during prometaphase. At metaphase, found in a filamentous structure that may be specifically associated with kinetochore microtubules. At anaphase, found at or near kinetochores of separating chromosomes. At the beginning of telophase, becomes excluded again from the nucleus and is dispersed in the cytoplasm (By similarity). Belongs to the ZW10 family.