Translational motors that depend on cytoskeletal elements, either actin or tubulin, for their activity are critical for cellular function in eukaryotes. Microtubule (MT)-dependent motors are broadly classified as dyneins and kinesins, based on sequence similarity. Typically, dyneins walk towards the minus-ends of MTs, while kinesins walk towards the plus-ends, with some plant and animal kinesins also seen to be minus-end Microtubule plus-and minus-end: The kinetic polarity of MTs with plus indicating net growth and minus net shrinkage. directed. While our understanding of motor mechanics at a single-molecule level has rapidly improved due to developments in force spectroscopy, in vivo motor transport often involves multiple motors acting together. Here, we review our current understanding of collective effects that emerge in motor-driven transport in vivo based on physical mechanisms inferred from in vitro reconstitution experiments involving MT transport, or ‘gliding assays’ Gliding Assay: Microtubule (MT) transport by immobilized molecular motors.. We discuss the evidence for number dependence in cargo transport at MT cross-overs, orientation sorting of MTs during axonal regeneration in neurons, spindle bipolarization by MT transport, and nuclear positioning during mitosis in the model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. We discuss how minimal in vitro gliding assays have been successfully used to identify the mechanical properties of collective motor transport that produce such cooperative effects. The ‘loose coupling’ mechanism of Oosawa, which was developed to explain the emergence of cooperation in collective motor transport, appears to be consistent with evidence from kinesin, but not dynein. Additionally, substrate rigidity also appears to play a role in collective force generation, as seen in lipid-anchorage studies of collective transport. Thus, a deeper understanding of the intra- and inter-motor properties of kinesins and dyneins Kinesin and Dynein: MT dependent molecular motors that walk predominantly towards the plus- and minus-ends of the MTs respectively., as well as non-motor effects due to the substrate is required, for the emergence of a complete picture of the in vivo mechanobiology of collective motor transport. Microtubule plus-and minus-end: The kinetic polarity of MTs with plus indicating net growth and minus net shrinkage. Gliding Assay: Microtubule (MT) transport by immobilized molecular motors. Kinesin and Dynein: MT dependent molecular motors that walk predominantly towards the plus- and minus-ends of the MTs respectively.

中文翻译：

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驱动蛋白和动力蛋白对微管集体转运的数量依赖性

依赖于细胞骨架元素（肌动蛋白或微管蛋白）的平移马达的活性对于真核生物的细胞功能至关重要。基于序列相似性，依赖微管 (MT) 的电机大致分为动力蛋白和驱动蛋白。通常，动力蛋白走向 MTs 的负端，而驱动蛋白走向正端，一些植物和动物驱动蛋白也被视为负端微管正负端：MTs 的动力学极性，加号表示净增长减去净收缩。导演。由于力谱的发展，我们在单分子水平上对运动力学的理解得到了迅速提高，但体内运动传输通常涉及多个电机共同作用。这里，我们回顾了我们目前对体内运动驱动运输中出现的集体效应的理解，这是基于从涉及 MT 运输的体外重建实验或“滑动试验”滑动试验：固定分子马达的微管 (MT) 运输推断出的物理机制。我们讨论了 MT 交叉处货物运输的数量依赖性、神经元轴突再生过程中 MT 的方向排序、MT 运输的纺锤体双极化以及模型酵母酿酒酵母和粟酒裂殖酵母有丝分裂期间核定位的证据。我们讨论了最小的体外滑翔试验如何成功地用于识别产生这种协同效应的集体运动运输的机械特性。大泽的“松耦合”机制，这是为了解释集体汽车运输中合作的出现而开发的，似乎与驱动蛋白的证据一致，但与动力蛋白的证据不一致。此外，如在集体运输的脂质锚定研究中所见，基质刚性似乎也在集体力的产生中发挥作用。因此，更深入地了解驱动蛋白和动力蛋白的运动内和运动间特性 驱动蛋白和动力蛋白：主要分别朝向 MT 的正负端移动的 MT 依赖性分子马达，以及非运动效应由于需要底物，才能出现集体运动运输的体内力学生物学的完整图景。微管正负端：MTs 的动力学极性，正表示净增长，负净收缩。滑翔试验：通过固定分子马达进行微管 (MT) 运输。驱动蛋白和动力蛋白：分别主要朝向 MT 的正负端移动的 MT 依赖分子马达。