Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA.
Department of Physics, University of Colorado, Boulder, Colorado 80302, USA.
Phys Rev E. 2016 Aug;94(2-1):022419. doi: 10.1103/PhysRevE.94.022419. Epub 2016 Aug 29.
Motor protein motion on biopolymers can be described by models related to the totally asymmetric simple exclusion process (TASEP). Inspired by experiments on the motion of kinesin-4 motors on antiparallel microtubule overlaps, we analyze a model incorporating the TASEP on two antiparallel lanes with binding kinetics and lane switching. We determine the steady-state motor density profiles using phase-plane analysis of the steady-state mean field equations and kinetic Monte Carlo simulations. We focus on the density-density phase plane, where we find an analytic solution to the mean field model. By studying the phase-space flows, we determine the model's fixed points and their changes with parameters. Phases previously identified for the single-lane model occur for low switching rate between lanes. We predict a multiple coexistence phase due to additional fixed points that appear as the switching rate increases: switching moves motors from the higher-density to the lower-density lane, causing local jamming and creating multiple domain walls. We determine the phase diagram of the model for both symmetric and general boundary conditions.
马达蛋白在生物聚合物上的运动可以通过与完全不对称简单排斥过程（TASEP）相关的模型来描述。受在反平行微管重叠上运动的 kinesin-4 马达实验的启发，我们分析了一个包含两条反平行车道上的 TASEP 的模型，其中包括结合动力学和车道切换。我们使用稳态平均场方程的相平面分析和动力学蒙特卡罗模拟来确定稳态马达密度分布。我们关注密度-密度相平面，在那里我们找到了平均场模型的解析解。通过研究相空间流，我们确定了模型的平衡点及其随参数的变化。在较低的车道切换率下，会出现单车道模型中已识别的相位。我们预测由于额外的固定点会出现多共存相：切换会将马达从高密度车道移动到低密度车道，导致局部堵塞并产生多个畴壁。我们确定了模型在对称和一般边界条件下的相图。
