Kinesin-8s hang on by a tail.

Accurate segregation of genetic material into two daughter cells is essential for organism reproduction, development, and survival. The cell assembles a macromolecular structure called the mitotic spindle, which is composed of dynamic microtubules (MTs) and many associated proteins that assemble the spindle and drive the segregation of the chromosomes. Members of the kinesin superfamily of MT associated proteins use the energy of ATP hydrolysis to help organize the spindle, to transport cargo within the spindle, and to regulate spindle MT dynamics. The Kinesin-8 and Kinesin-13 families are involved in controlling mitotic spindle morphology, spindle positioning, and chromosome movement. While both kinesin families are MT destabilizing enzymes, it is unclear whether their mechanisms of MT destabilization are mechanistically similar or how they act to destabilize MTs. Recently, three groups identified an additional MT binding domain within the tail of Kinesin-8s that is essential for their roles in regulating MT dynamics and chromosome positioning.