Physics of Life Processes, Leiden Institute of Physics, Leiden University, Leiden, The Netherlands.
Biophys J. 2010 Sep 22;99(6):1835-41. doi: 10.1016/j.bpj.2010.06.071.
Collections of motors dynamically organize to extract membrane tubes. These tubes grow but often pause or change direction as they traverse an underlying microtubule (MT) network. In vitro, membrane tubes also stall: they stop growing in length despite a large group of motors available at the tip to pull them forward. In these stationary membrane tubes in vitro, we find that clusters of processive kinesin motors form and reach the tip of the tube at regular time intervals. The average times between cluster arrivals depends on the time over which motors depart from the tip, suggesting that motors are recycled toward the tip. Numerical simulations of the motor dynamics in the membrane tube and on the MTs show that the presence of cooperative binding between motors quantitatively accounts for the clustering observed experimentally. Cooperative binding along the length of the MT and a nucleation point at a distance behind the tip define the recycling period. Based on comparison of the numerical results and experimental data, we estimate a cooperative binding probability and concentration regime where the recycling phenomenon occurs.
马达的集合体动态组织起来以提取膜管。这些管在生长，但在穿过下面的微管（MT）网络时经常暂停或改变方向。在体外，膜管也会停滞：尽管尖端有大量的马达可以拉动它们向前，但它们的长度不再增长。在体外这些静止的膜管中，我们发现，连续运动的驱动蛋白马达簇形成并以固定的时间间隔到达管的尖端。簇到达的平均时间间隔取决于马达从尖端离开的时间，这表明马达被回收至尖端。对膜管和 MT 上的马达动力学的数值模拟表明，马达之间的合作结合定量地解释了实验中观察到的聚集现象。沿 MT 的长度的合作结合以及在尖端后面的距离处的成核点定义了回收周期。基于数值结果和实验数据的比较，我们估计了一个合作结合概率和浓度范围，在此范围内会发生回收现象。
