Müller Melanie J I, Klumpp Stefan, Lipowsky Reinhard
Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
Proc Natl Acad Sci U S A. 2008 Mar 25;105(12):4609-14. doi: 10.1073/pnas.0706825105. Epub 2008 Mar 17.
Intracellular transport is based on molecular motors that pull cargos along cytoskeletal filaments. One motor species always moves in one direction, e.g., conventional kinesin moves to the microtubule plus end, whereas cytoplasmic dynein moves to the microtubule minus end. However, many cellular cargoes are observed to move bidirectionally, involving both plus- and minus-end-directed motors. The presumably simplest mechanism for such bidirectional transport is provided by a tug-of-war between the two motor species. This mechanism is studied theoretically using the load-dependent transport properties of individual motors as measured in single-molecule experiments. In contrast to previous expectations, such a tug-of-war is found to be highly cooperative and to exhibit seven different motility regimes depending on the precise values of the single motor parameters. The sensitivity of the transport process to small parameter changes can be used by the cell to regulate its cargo traffic.
细胞内运输基于分子马达，这些分子马达沿着细胞骨架细丝拉动货物。一种马达总是朝一个方向移动，例如，传统驱动蛋白向微管正端移动，而胞质动力蛋白向微管负端移动。然而，观察到许多细胞货物双向移动，涉及正端和负端定向的马达。这种双向运输可能最简单的机制是由两种马达之间的拔河提供的。利用单分子实验中测量的单个马达的负载依赖性运输特性，从理论上研究了这种机制。与先前的预期相反，发现这种拔河高度协同，并根据单个马达参数的精确值表现出七种不同的运动状态。细胞可以利用运输过程对小参数变化的敏感性来调节其货物运输。
