Microtubules are orientated microscopic tubes that are part of the skeleton of living cells. In this animation, four microtubules form an antiparallel bundle where the pink microtubules are orientated opposite to the green and orange ones. This specific arrangement is found for example in the mitotic spindle, where it contributes to the separation of the chromosomes. Antiparallel bundles are stabilised by specialised crosslinkers (blue) that can diffuse longitudinally along microtubules, and also connect adjacent microtubules. In addition, the bi-headed kinesins (green), found associated with these crosslinkers, are molecular motors that can move along microtubules. By gently pulling the diffusible crosslinkers, kinesins will eventually slide the microtubules relative to each other, shortening the overlap region and elongating the bundle, an essential feature for such a cellular structure.
Credits: Manuel Lera-Ramirez and Francois Nedelec