IDENTIFICATION AND PARTIAL CHARACTERIZATION OF MITOTIC CENTROMERE-ASSOCIATED KINESIN, A KINESIN-RELATED PROTEIN THAT ASSOCIATES WITH CENTROMERES DURING MITOSIS

Using antipeptide antibodies to conserved regions of the kinesin motor domain, we cloned a kinesin-related protein that associates with the centromere region of mitotic chromosomes. We call the protein MCAK, fo r mitotic centromere-associated kinesin. MCAK appears concentrated on centromeres at prophase and persists until telophase, after which time the localization disperses. It is found throughout the centromere reg ion and between the kinetochore plates of isolated mitotic CHO chromos omes, in contrast to two other kinetochore-associated microtubule moto rs: cytoplasmic dynein and CENP-E (Yen et al., 1992), which are closer to the outer surface of the kinetochore plates. Sequence analysis sho ws MCAK to be a kinesin-related protein with the motor domain located in the center of the protein. It is 60-70% similar to kif2, a kinesin- related protein originally cloned from mouse brain with a centrally lo cated motor domain (Aizawa et al., 1992). MCAK protein is present in i nterphase and mitotic CHO cells and is transcribed as a single 3.4-kb message.