Cilia are hairlike protrusions that project from the surface of eukaryotic cells and play key roles in cell signaling and motility. Ciliary motility is regulated by the conserved nexin-dynein regulatory complex (N-DRC), which links adjacent doublet microtubules and regulates and coordinates the activity of outer doublet complexes. Despite its critical role in cilia motility, the assembly and molecular basis of the regulatory mechanism are poorly understood. Here, using cryo-electron microscopy in conjunction with biochemical cross-linking and integrative modeling, we localize 12 DRC subunits in the N-DRC structure of Tetrahymena thermophila. We also find that the CCDC96/113 complex is in close contact with the DRC9/10 in the linker region. In addition, we reveal that the N-DRC is associated with a network of coiled-coil proteins that most likely mediates N-DRC regulatory activity.

纤毛是从真核细胞表面突出的毛发状突起，在细胞信号传导和运动中发挥关键作用。纤毛运动由保守的连接蛋白-动力蛋白调节复合物（N-DRC）调节，该复合物连接相邻的双联体微管并调节和协调外部双联体复合物的活性。尽管其在纤毛运动中发挥着关键作用，但其调节机制的组装和分子基础却知之甚少。在这里，我们使用冷冻电子显微镜结合生化交联和综合建模，在嗜热四膜虫的 N-DRC 结构中定位了 12 个 DRC 亚基。我们还发现 CCDC96/113 复合物与 DRC9/10 的连接区紧密相连。此外，我们还发现 N-DRC 与卷曲螺旋蛋白网络相关，该网络很可能介导 N-DRC 调节活性。