Chlamydomonas ARMC2/PF27 is an obligate cargo adapter for intraflagellar transport of radial spokes.
Chlamydomonas ARMC2/PF27 is an obligate cargo adapter for intraflagellar transport of radial spokes.
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作者：
Lechtreck KF;Liu Y;Dai J;Alkhofash RA;Butler J;Alford L;Yang P
鞭毛内转运(IFT)将蛋白质携带到鞭毛中，但IFT序列如何与组装鞭毛所需的大量不同蛋白质相互作用在很大程度上尚不清楚。在这里，我们证明衣藻属放射状辐条的IFT需要ARMC2/PF27，这是一种与男性不育症和肺功能降低相关的保守的螳螂重复蛋白。衣藻ARMC2在生长鞭毛中高度富含，标记的ARMC2和辐条蛋白RSP3在顺行序列上共同迁移。相比之下，货物和内外动力臂适配器独立于ARMC2移动，表明无关的货物随机分布在IFT列车上。在鞭毛顶端同时卸载后，RSP3附着在轴丝上，而ARMC2扩散回细胞体。在armc2/pf27突变体中，径向辐条的IFT被取消，径向辐条的存在仅限于鞭毛的近端区域。我们得出结论，ARMC2是径向辐条IFT所需的货物适配器，以确保其沿鞭毛组装。ARMC2是一种日益增长的货物特异性适配器，能够通过IFT实现预先组装的轴丝亚结构的鞭毛运输。
Intraflagellar transport (IFT) carries proteins into flagella but how IFT trains interact with the large number of diverse proteins required to assemble flagella remains largely unknown. Here, we show that IFT of radial spokes in Chlamydomonas requires ARMC2/PF27, a conserved armadillo repeat protein associated with male infertility and reduced lung function. Chlamydomonas ARMC2 was highly enriched in growing flagella and tagged ARMC2 and the spoke protein RSP3 co-migrated on anterograde trains. In contrast, a cargo and an adapter of inner and outer dynein arms moved independently of ARMC2, indicating that unrelated cargoes distribute stochastically onto the IFT trains. After concomitant unloading at the flagellar tip, RSP3 attached to the axoneme whereas ARMC2 diffused back to the cell body. In armc2/pf27 mutants, IFT of radial spokes was abolished and the presence of radial spokes was limited to the proximal region of flagella. We conclude that ARMC2 is a cargo adapter required for IFT of radial spokes to ensure their assembly along flagella. ARMC2 belongs to a growing class of cargo-specific adapters that enable flagellar transport of preassembled axonemal substructures by IFT.