Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, USA.
J Biol Chem. 2010 Aug 20;285(34):26608-17. doi: 10.1074/jbc.M110.104661. Epub 2010 Jun 10.
Without guidance cues, cytoskeletal motors would traffic components to the wrong destination with disastrous consequences for the cell. Recently, we identified a motor protein, myosin X, that identifies bundled actin filaments for transport. These bundles direct myosin X to a unique destination, the tips of cellular filopodia. Because the structural and kinetic features that drive bundle selection are unknown, we employed a domain-swapping approach with the nonselective myosin V to identify the selectivity module of myosin X. We found a surprising role of the myosin X tail region (post-IQ) in supporting long runs on bundles. Moreover, the myosin X head is adapted for initiating processive runs on bundles. We found that the tail is structured and biases the orientation of the two myosin X heads because a targeted insertion that introduces flexibility in the tail abolishes selectivity. Together, these results suggest how myosin motors may manage to read cellular addresses.
没有导向线索，细胞骨架马达会将成分错误地运输到目的地，对细胞造成灾难性的后果。最近，我们发现了一种肌球蛋白蛋白 X，它可以识别成束的肌动蛋白丝进行运输。这些束将肌球蛋白 X 引导到一个独特的目的地，即细胞丝状伪足的尖端。由于驱动束选择的结构和动力学特征尚不清楚，我们采用了一种结构域交换方法，用非选择性肌球蛋白 V 来鉴定肌球蛋白 X 的选择性模块。我们发现肌球蛋白 X 尾部区域（后 IQ 区）在支持在束上的长距离运行中起着惊人的作用。此外，肌球蛋白 X 的头部适合于在束上启动连续运行。我们发现，尾部的结构会影响两个肌球蛋白 X 头部的取向，因为尾部的靶向插入会引入尾部的灵活性，从而消除选择性。总之，这些结果表明肌球蛋白马达如何能够读取细胞地址。
