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Mol Biol Cell. 2019 Mar 15;30(6):753-765. doi: 10.1091/mbc.E18-08-0541. Epub 2019 Jan 23.

A unified model for microtubule rescue.

Author information

1
Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045.

Abstract

How microtubules transition from depolymerization to polymerization, known as rescue, is poorly understood. Here we examine two models for rescue: 1) an "end-driven" model in which the depolymerizing end stochastically switches to a stable state; and 2) a "lattice-driven" model in which rescue sites are integrated into the microtubule before depolymerization. We test these models using a combination of computational simulations and in vitro experiments with purified tubulin. Our findings support the "lattice-driven" model by identifying repeated rescue sites in microtubules. In addition, we discover an important role for divalent cations in determining the frequency and location of rescue sites. We use "wash-in" experiments to show that divalent cations inhibit rescue during depolymerization, but not during polymerization. We propose a unified model in which rescues are driven by embedded rescue sites in microtubules, but the activity of these sites is influenced by changes in the depolymerizing ends.

PMID:
30672721
DOI:
10.1091/mbc.E18-08-0541

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