Has a dual function in spindle-assembly checkpoint signaling and in promoting the establishment of correct kinetochore-microtubule (K-MT) attachments (PubMed:18248670, PubMed:19109417, PubMed:25987605). Promotes the formation of stable end-on bipolar attachments of chromosomes (PubMed:25987605). Necessary for expression and kinetochore localization of bub-1 (PubMed:19109417, PubMed:25987605). Plays a role in synapsis checkpoint signaling inducing apoptosis in response to unsynapsed chromosomes and thus controlling chromosomal segregation during oocyte meiosis (PubMed:26483555). May interact with bub-1; for localization at the kinetochore and the onset of anaphase. Localizes at kinetochores on condensing chromosomes in late prophase and during metaphase (PubMed:19109417). Localization to the kinetochore is dependent on bub-1 (PubMed:25987605). Viable, but with a reduced brood size (PubMed:25987605). Reduced bub-1 expression and localization at the kinetochore which may lead to the delay in the onset of anaphase during embryogenesis (PubMed:25987605). Defective synapsis with increased numbers of nuclei that contain asymmetrically aligned (clustered) chromosomes (PubMed:26483555). RNAi-mediated knockdown results in reduced survival as compared to wild-type animals in anoxic conditions (PubMed:18248670). Belongs to the WD repeat BUB3 family.