In animals and fungi, cytoplasmic dynein is a processive minus-end-directed motor that plays dominant roles in various intracellular processes. In contrast, land plants lack cytoplasmic dynein but contain many minus-end-directed kinesin-14s. No plant kinesin-14 is known to produce processive motility as a homodimer. OsKCH2 is a plant-specific kinesin-14 with an N-terminal actin-binding domain and a central motor domain flanked by two predicted coiled-coils (CC1 and CC2). Here, we show that OsKCH2 specifically decorates preprophase band microtubules in vivo and transports actin filaments along microtubules in vitro. Importantly, OsKCH2 exhibits processive minus-end-directed motility on single microtubules as individual homodimers. We find that CC1, but not CC2, forms the coiled-coil to enable OsKCH2 dimerization. Instead, our results reveal that removing CC2 renders OsKCH2 a nonprocessive motor. Collectively, these results show that land plants have evolved unconventional kinesin-14 homodimers with inherent minus-end-directed processivity that may function to compensate for the loss of cytoplasmic dynein.

中文翻译：

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前期带相关的驱动蛋白14 OsKCH2是一种负性的，末端负性的微管马达。

在动物和真菌中，细胞质动力蛋白是一种负性的过程，在多种细胞内过程中起主导作用。相反，陆地植物缺乏细胞质动力蛋白，但含有许多负端导向的驱动蛋白14s。尚无植物驱动蛋白14作为同型二聚体产生进行性运动。OsKCH2是一种植物特异性驱动蛋白14，具有N端肌动蛋白结合域和中央运动域，两侧是两个预测​​的卷曲螺旋（CC1和CC2）。在这里，我们显示OsKCH2在体内特异性装饰前相带微管，并在体外沿微管运输肌动蛋白丝。重要的是，OsKCH2作为单个同二聚体在单个微管上表现出进行性的负端定向运动。我们发现CC1而非CC2形成了线圈线圈以实现OsKCH2二聚化。反而，我们的结果表明，删除CC2会使OsKCH2成为非过程性电动机。总体而言，这些结果表明，陆地植物已进化出具有固有的负末端定向的合成能力的非常规驱动蛋白14同型二聚体，其功能可能是补偿细胞质动力蛋白的损失。