Fig. 5. A Monte-Carlo simulation shows that transiently binding IFs stabilize dynamic microtubules.

a Illustration of the reaction rates (top) and simulated microtubule lattice with 13 protofilaments and a seam with a longitudinal displacement of 1.5 dimers (bottom). b Typical simulated microtubule growing from a GMPCPP (guanylyl-(α,β)-methylene-diphosphonate) seed with dimers either in the GTP (purple) or in the GDP state (cyan). c Typical length-time plot (kymograph) of a simulated microtubule in 20 μM free tubulin solution without vimentin tetramers (left) or in 25 μM free tubulin solution with 2.3 μM vimentin tetramers (right). d–f We reproduced the experimental data shown in Fig. 1d–g (shown here in a semi-transparent fashion, for a vimentin concentration of 2.3 μM) with our Monte-Carlo simulation (opaque). d Addition of vimentin neither changes the experimental nor the simulated microtubule growth rates at 20 or 25 μM. Boxplots include the median as the center line, the 25th and 75th percentiles as box limits, and the entire data range as whiskers. For clarity, the entire data range of the experimental data is not shown here, but is presented in Fig. 1. e Addition of vimentin lowers the catastrophe frequency of dynamic microtubules for both tubulin concentrations studied here. f In case of 25 μM free tubulin, the rescue rate increases due to the stabilizing effect of the surrounding vimentin IFs. The circle areas scale with the total microtubule depolymerization time as in the representation of the experimental data. All tubulin and vimentin concentrations are input concentrations. Source data are provided as a Source Data file.