Ross Jennifer L, Wallace Karen, Shuman Henry, Goldman Yale E, Holzbaur Erika L F
Department of Physiology and Pennsylvania Muscle Institute, University of Pennsylvania, Philadelphia, PA 19104, USA.
Nat Cell Biol. 2006 Jun;8(6):562-70. doi: 10.1038/ncb1421. Epub 2006 May 21.
Cytoplasmic dynein is the primary molecular motor responsible for transport of vesicles, organelles, proteins and RNA cargoes from the periphery of the cell towards the nucleus along the microtubule cytoskeleton of eukaryotic cells. Dynactin, a large multi-subunit activator of dynein, docks cargo to the motor and may enhance dynein processivity. Here, we show that individual fluorescently labelled dynein-dynactin complexes exhibit bidirectional and processive motility towards both the plus and minus ends of microtubules. The dependence of this activity on substrate ATP concentration, nucleotide analogues and inhibitors suggests that bidirectional motility is an active energy-transduction property of dynein-dynactin motor mechano-chemistry. The unique motility characteristics observed may reflect the flexibility of the dynein structure that leads to an enhanced ability to navigate around obstacles in the cell.
胞质动力蛋白是主要的分子马达，负责沿着真核细胞的微管细胞骨架将囊泡、细胞器、蛋白质和RNA货物从细胞周边向细胞核运输。动力蛋白激活蛋白是一种大型多亚基动力蛋白激活剂，它将货物对接至马达，并可能增强动力蛋白的持续运动能力。在此，我们表明单个荧光标记的动力蛋白-动力蛋白激活蛋白复合物对微管的正端和负端均表现出双向和持续运动性。这种活性对底物ATP浓度、核苷酸类似物和抑制剂的依赖性表明，双向运动性是动力蛋白-动力蛋白激活蛋白马达机械化学的一种主动能量转导特性。观察到的独特运动特性可能反映了动力蛋白结构的灵活性，这导致其在细胞中绕过障碍物的能力增强。
