Ligon Lee A, Tokito Mariko, Finklestein Jeffrey M, Grossman Francesca E, Holzbaur Erika L F
Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6085, USA.
J Biol Chem. 2004 Apr 30;279(18):19201-8. doi: 10.1074/jbc.M313472200. Epub 2004 Feb 24.
Cytoplasmic dynein and kinesin I are both unidirectional intracellular motors. Dynein moves cargo toward the cell center, and kinesin moves cargo toward the cell periphery. There is growing evidence that bi-directional motility is regulated in the cell, potentially through direct interactions between oppositely oriented motors. We have identified a direct interaction between cytoplasmic dynein and kinesin I. Using the yeast two-hybrid assay and affinity chromatography, we demonstrate that the intermediate chain of dynein binds to kinesin light chains 1 and 2. The interaction is both direct and specific. Co-immunoprecipitation experiments demonstrate an interaction between endogenous proteins in rat brain cytosol. Double-label immunocytochemistry reveals a partial co-localization of vesicle-associated motor proteins. Together these observations suggest that soluble motors can interact, potentially allowing kinesin I to actively localize dynein to cellular sites of function. There is also a vesicle population with both dynein and kinesin I bound that may be capable of bi-directional motility along cellular microtubules.
胞质动力蛋白和驱动蛋白I都是单向的细胞内马达蛋白。动力蛋白将货物向细胞中心移动，而驱动蛋白则将货物向细胞周边移动。越来越多的证据表明，细胞中的双向运动是受调控的，可能是通过方向相反的马达蛋白之间的直接相互作用来实现。我们已经确定了胞质动力蛋白和驱动蛋白I之间的直接相互作用。利用酵母双杂交试验和亲和层析，我们证明动力蛋白的中间链与驱动蛋白轻链1和2结合。这种相互作用是直接且特异的。免疫共沉淀实验证明了大鼠脑细胞质中内源性蛋白之间的相互作用。双标记免疫细胞化学揭示了囊泡相关马达蛋白的部分共定位。这些观察结果共同表明，可溶性马达蛋白可以相互作用，这可能使驱动蛋白I将动力蛋白主动定位到细胞功能位点。也存在一种同时结合了动力蛋白和驱动蛋白I的囊泡群体，它们可能能够沿着细胞微管进行双向运动。
