Insights into the role of phosphorylation on microtubule crosslinking by PRC1.

The mitotic spindle is composed of distinct networks of microtubules, including interpolar bundles that can bridge sister kinetochore fibers and bundles that organize the spindle midzone in anaphase. The crosslinking protein PRC1 can mediate such bundling interactions between antiparallel microtubules. PRC1 is a substrate of mitotic kinases including CDK/cyclin-B, suggesting that it can be phosphorylated in metaphase and dephosphorylated in anaphase.

Two modes of PRC1-mediated mechanical resistance to kinesin-driven microtubule network disruption.

The proper organization of the microtubule-based spindle during cell division requires the collective activity of many different proteins. These include non-motor microtubule-associated proteins (MAPs), whose functions include crosslinking microtubules to regulate filament sliding rates and assemble microtubule arrays. One such protein is PRC1, an essential MAP that has been shown to preferentially crosslink overlapping antiparallel microtubules at the spindle midzone.