Model predictions for MT dynamics in bundles in the presence of MAP65.

<p>Simulations were performed with MAP65 binding rates of k_on = 10 µM.s⁻¹, k_off = 0 s⁻¹, and MAP65 concentration of 0.1 µM; the number of MTs in the bundle is 10. The MAP65 removal probabilities are, for MAP65-1, <i>pR_ap</i> = 0.1 and <i>pR_p</i> = 0.8, for MAP65-4, <i>pR_ap</i> = <i>pR_p</i> = 0.7, and for MAP-X <i>pR_ap</i> = 0.8 and <i>pR_p</i> = 0.1. In marked contrast with MAP65-1, the hypothetical MAP-X favors pairs of parallel MT (low <i>pR_p</i> and high <i>pR_ap</i>). In control conditions, we have <i>pR_ap</i> = <i>pR_p</i> = 1. Each distribution curve corresponds to 20 independent model runs. (<b>A</b>)<b>.</b> The distribution of polymerization length (left column) or depolymerization length (right column) is shown for all (+, top row) and (-, bottom row) MT ends in the bundle. The inset shows the depolymerization of the control bundle. Note the change in the scale of the abscissa axis. (<b>B</b>)<b>.</b> Average distance between the longest (leader) MT and the shortest MT (last MT follower) (L_max−L_min) in the bundle. (<b>C</b>)<b>.</b> Average distance between the leader MT and the next follower MT (L_max−L_follow). (<b>D</b>)<b>.</b> Cartoon showing how (L_max−L_min) and (L_max−L_follow) are defined. Note that the identity of the leader and follower MTs can change in the course of time. The seed and the dynamic section of each MT are shown respectively in red and in green.