A shear lag analysis predicts the strong size effect on the persistence length of microtubules

Abstract

As one essential component in cytoskeleton, the persistence length of a microtubule was reported to strongly depend on its contour length. To understand this intriguing size effect, here we develop a composite model for a microtubule with an adapted shear lag analysis. A characteristic length is identified, over which the persistence length of a microtubule monotonously increases with its contour length until it saturates, in consistency with the experimental data. This work clearly shows that shear lag between neighboring protofilaments due to the highly anisotropy leads to the strong size effect on the persistence lengths of microtubules.