@article {Fees401372, author = {Colby P. Fees and Jeffrey K. Moore}, title = {A unified model for microtubule rescue}, elocation-id = {401372}, year = {2018}, doi = {10.1101/401372}, publisher = {Cold Spring Harbor Laboratory}, abstract = {How microtubules transition from depolymerization to polymerization, known as rescue, is poorly understood. Here we examine two models for rescue: 1) an {\textquoteleft}end-driven{\textquoteright} model in which the depolymerizing end stochastically switches to a stable state; and 2) a {\textquoteleft}lattice-driven{\textquoteright} model in which rescue-sites are integrated into the microtubule prior to depolymerization. We test these models using a combination of computational simulations and in vitro experiments with purified tubulin. Our findings support the {\textquoteleft}lattice-driven{\textquoteright} 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 {\textquoteleft}wash-in{\textquoteright} experiments to show that divalent cations inhibit rescue during depolymerization, but not during the 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.}, URL = {https://www.biorxiv.org/content/early/2018/08/27/401372}, eprint = {https://www.biorxiv.org/content/early/2018/08/27/401372.full.pdf}, journal = {bioRxiv} }