Actin to completion

The actin cytoskeleton is alone on the cytokinesis stage no longer. The final step of cytokinesis cannot be completed without interactions between actin and a microtubule-interacting protein, CHO1, according to a new study by Kuriyama et al. on page 783.Organization of microtubules into the central spindle is achieved in part by the MKLP1 microtubule-binding motor protein. Kuriyama has determined that alternative splicing of MKLP1 generates CHO1, which has an additional 100 amino acids in the COOH-terminal tail. The group shows that MKLP1 and CHO1 are coexpressed within mammalian cells, both tightly associated with microtubules.

Although CHO1 associates with microtubules, Kuriyama et al. show that it is not required for chromosome separation. The unique CHO1 region imparted an unexpected actin-binding activity both in vitro and in vivo. Inhibition of this actin binding did not impair early steps in...