Tao Y C, Peskin C S
Department of Physics, New York University, New York 10003, USA.
Biophys J. 1998 Sep;75(3):1529-40. doi: 10.1016/S0006-3495(98)74072-X.
In this paper we present a model that simulates the role of microtubules in depolymerization-driven transport. The model simulates a system that consists of a 13-protofilament microtubule with "five-start" helical structure and a motor protein-coated bead that moves along one of the protofilaments of the microtubule, as in in vitro experiments. The microtubule is simulated using the lateral cap model, with substantial generalizations. For the new terminal configurations in the presence of the bead, rate constants for association and dissociation events of tubulin molecules are calculated by exploring the geometric similarities between different patterns of terminal configurations and by decomposing complex patterns into simpler patterns whose corresponding rate constants are known. In comparison with a previous model, in which simplifications are made about the structure of the microtubule and in which the microtubule can only depolymerize, the detailed structure of the microtubule is taken into account in the present model. Furthermore, the microtubule can be either polymerizing or depolymerizing. Force-velocity curves are obtained for both zero and non-zero tubulin guanosine 5'-triphosphate (GTP) concentrations. By analyzing the trajectory of the bead under different parameters, the condition for "run and pause" is analyzed, and the time scale of "run" and "pause" is found to be different for different motor proteins. We also suggest experiments that can be used to examine the results predicted by the model.
在本文中，我们提出了一个模拟微管在解聚驱动运输中作用的模型。该模型模拟了一个系统，该系统由具有“五起始”螺旋结构的13原纤维微管和一个沿微管的其中一条原纤维移动的、涂有运动蛋白的珠子组成，如同体外实验那样。微管是使用侧向帽模型进行模拟的，并做了大量推广。对于存在珠子时的新末端构型，通过探索不同末端构型模式之间的几何相似性，并将复杂模式分解为已知相应速率常数的更简单模式，来计算微管蛋白分子结合和解离事件的速率常数。与之前的模型相比，之前的模型对微管结构进行了简化，且微管只能解聚，而本模型考虑了微管的详细结构。此外，微管既可以聚合也可以解聚。在微管蛋白鸟苷5'-三磷酸（GTP）浓度为零和非零的情况下都获得了力-速度曲线。通过分析不同参数下珠子的轨迹，分析了“运行和暂停”的条件，并且发现不同运动蛋白的“运行”和“暂停”时间尺度不同。我们还提出了可用于检验该模型预测结果的实验。
