Limited Resources Induce Bistability in Microtubule Length Regulation
Matthias Rank (Ludwig Maximilians University)
Aniruddha Mitra (Max Planck Institute of Molecular Cell Biology and Genetics, Technische Universität Dresden)
Louis Reese (TU Delft - BN/Marileen Dogterom Lab, Kavli institute of nanoscience Delft)
Stefan Diez (Max Planck Institute of Molecular Cell Biology and Genetics, Technische Universität Dresden)
Erwin Frey (Ludwig Maximilians University)
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Abstract
The availability of protein is an important factor for the determination of the size of the mitotic spindle. Involved in spindle-size regulation is kinesin-8, a molecular motor and microtubule (MT) depolymerase, which is known to tightly control MT length. Here, we propose and analyze a theoretical model in which kinesin-induced MT depolymerization competes with spontaneous polymerization while supplies of both tubulin and kinesin are limited. In contrast to previous studies where resources were unconstrained, we find that, for a wide range of concentrations, MT length regulation is bistable. We test our predictions by conducting in vitro experiments and find that the bistable behavior manifests in a bimodal MT length distribution.
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