The intraflagellar transport (IFT) machinery consists of the anterograde motor kinesin‐II, the retrograde motor IFT dynein, and the IFT‐A and ‐B complexes. However, the interaction among IFT motors and IFT complexes during IFT remains elusive. Here, we show that the IFT‐B protein IFT54 interacts with both kinesin‐II and IFT dynein and regulates anterograde IFT. Deletion of residues 342–356 of Chlamydomonas IFT54 resulted in diminished anterograde traffic of IFT and accumulation of IFT motors and complexes in the proximal region of cilia. IFT54 directly interacted with kinesin‐II and this interaction was strengthened for the IFT54^Δ342–356 mutant in vitro and in vivo. The deletion of residues 261–275 of IFT54 reduced ciliary entry and anterograde traffic of IFT dynein with accumulation of IFT complexes near the ciliary tip. IFT54 directly interacted with IFT dynein subunit D1bLIC, and deletion of residues 261–275 reduced this interaction. The interactions between IFT54 and the IFT motors were also observed in mammalian cells. Our data indicate a central role for IFT54 in binding the IFT motors during anterograde IFT.

中文翻译：

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IFT54 直接与 kinesin-II 和 IFT 动力蛋白相互作用以调节顺行鞭毛内运输

鞭毛内运输 (IFT) 机制由顺行运动驱动蛋白-II、逆行运动 IFT 动力蛋白和 IFT-A 和 -B 复合物组成。然而，在 IFT 期间 IFT 电机和 IFT 复合体之间的相互作用仍然难以捉摸。在这里，我们表明 IFT-B 蛋白 IFT54 与驱动蛋白-II 和 IFT 动力蛋白相互作用并调节顺行 IFT。删除衣藻IFT54的残基 342-356导致 IFT 的顺行交通减少以及 IFT 马达和复合物在纤毛近端区域的积累。IFT54 直接与驱动蛋白-II 相互作用，并且这种相互作用在体外和体内的 IFT54 ^Δ342-356突变体中得到了加强. IFT54 残基 261-275 的缺失减少了 IFT 动力蛋白的纤毛进入和顺行交通，同时 IFT 复合物在睫状体尖端附近的积累。IFT54 直接与 IFT 动力蛋白亚基 D1bLIC 相互作用，残基 261-275 的缺失减少了这种相互作用。在哺乳动物细胞中也观察到 IFT54 和 IFT 电机之间的相互作用。我们的数据表明 IFT54 在顺行 IFT 期间结合 IFT 电机的核心作用。