Peskin C S, Oster G F
Courant Institute of Mathematical Sciences, New York, New York 10012, USA.
Biophys J. 1995 Dec;69(6):2268-76. doi: 10.1016/S0006-3495(95)80097-4.
Experiments indicate that depolymerization of microtubules generates sufficient force to produce the minus-end-directed transport of chromosomes during mitosis (Koshland et al., 1988). In vitro, analogous transport of kinesin-coated microspheres exhibits a paradoxical effect. Minus-end-directed transport of the microspheres driven by depolymerization is enhanced by the presence of ATP, which fuels the motor action of kinesin driving the microspheres in the opposite direction, toward the plus end of the microtubule. Here we present a mathematical model to explain this behavior. We postulate that a microsphere at the plus end of the microtubule facilitates depolymerization and hence enhances minus-end-directed transport. The force-velocity curve of the model is derived; it has the peculiar feature that velocity is maximal at some positive load (opposing the motion) rather than at zero load. The model is used to simulate the stochastic process of microsphere-facilitated depolymerization-driven transport. Simulated trajectories at low load show distinctive runs and pauses, the statistics of which are calculated from the model. The statistics of the process provide sufficient information to determine all of the model's parameters.
实验表明，微管解聚产生的力足以在有丝分裂期间产生向负端的染色体运输（Koshland等人，1988年）。在体外，类似的驱动蛋白包被微球的运输表现出一种矛盾的效应。由解聚驱动的微球向负端的运输因ATP的存在而增强，ATP为驱动蛋白的运动提供能量，驱动蛋白将微球向相反方向，即微管的正端驱动。在此，我们提出一个数学模型来解释这种行为。我们假设微管正端的微球促进解聚，从而增强向负端的运输。推导了该模型的力-速度曲线；它具有一个特殊的特征，即速度在某个正负载（与运动方向相反）时最大，而不是在零负载时最大。该模型用于模拟微球促进解聚驱动运输的随机过程。低负载下的模拟轨迹显示出明显的运行和停顿，其统计数据由模型计算得出。该过程的统计数据提供了足够的信息来确定模型的所有参数。
