Required for the spindle checkpoint attachment response during spindle formation, kinetochore microtubule interactions and chromosome segregation during anaphase. Ark1 activity depends upon cut17 function and phosphorylation. Ark1 with bir1 is required for full-scale association with kinetochores and formation of a complex with mad3. Ark1 is also required for phosphorylation of histone H3 that accompanies chromosome condensation and condensin recruitment to mitotic chromatin. Ark1 with pic1 is required for the execution of cytokinesis. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with bir1 and mad3 to form part of the mad2 complex involved in checkpoint activation. Interacts with pic1. Associates with the elongating spindle during anaphase. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. Aurora subfamily.