Kinesin-4 KIF21B is a potent microtubule pausing factor

• Main Authors: Wilhelmina E van Riel, Ankit Rai, Sarah Bianchi, Eugene A Katrukha, Qingyang Liu, Albert JR Heck, Casper C Hoogenraad, Michel O Steinmetz, Lukas C Kapitein, Anna Akhmanova
• Format: Article
• Language: English
• Published: eLife Sciences Publications Ltd 2017-03-01
• Series: eLife
• Subjects: microtubule dynamics; Kinesin; EB1; Kinesin-4; KIF21B; pausing
• Online Access: https://elifesciences.org/articles/24746

Microtubules are dynamic polymers that in cells can grow, shrink or pause, but the factors that promote pausing are poorly understood. Here, we show that the mammalian kinesin-4 KIF21B is a processive motor that can accumulate at microtubule plus ends and induce pausing. A few KIF21B molecules are sufficient to induce strong growth inhibition of a microtubule plus end in vitro. This property depends on non-motor microtubule-binding domains located in the stalk region and the C-terminal WD40 domain. The WD40-containing KIF21B tail displays preference for a GTP-type over a GDP-type microtubule lattice and contributes to the interaction of KIF21B with microtubule plus ends. KIF21B also contains a motor-inhibiting domain that does not fully block the interaction of the protein with microtubules, but rather enhances its pause-inducing activity by preventing KIF21B detachment from microtubule tips. Thus, KIF21B combines microtubule-binding and regulatory activities that together constitute an autonomous microtubule pausing factor.