Cilia and flagella serve as cellular antennae and propellers in various eukaryotic cells, and contain specific receptors and ion channels as well as components of axonemal microtubules and molecular motors to achieve their sensory and motile functions. Not only the bidirectional trafficking of specific proteins within cilia but also their selective entry and exit across the ciliary gate is mediated by the intraflagellar transport (IFT) machinery with the aid of motor proteins. The IFT-B complex, which is powered by the kinesin-2 motor, mediates anterograde protein trafficking from the base to the tip of cilia, whereas the IFT-A complex together with the dynein-2 complex mediates retrograde protein trafficking. The BBSome complex connects ciliary membrane proteins to the IFT machinery. Defects in any component of this trafficking machinery lead to abnormal ciliogenesis and ciliary functions, and results in a broad spectrum of disorders, collectively called the ciliopathies. In this review article, we provide an overview of the architectures of the components of the IFT machinery and their functional interplay in ciliary protein trafficking.

纤毛和鞭毛在各种真核细胞中充当细胞触角和螺旋桨，并包含特定的受体和离子通道以及轴突微管和分子马达的成分，以实现其感觉和运动功能。不仅鞭毛内特定蛋白的双向运输，而且通过鞭毛内运输（IFT）机器借助运动蛋白介导纤毛内特定蛋白的选择性进入和退出。由kinesin-2电机驱动的IFT-B复合物介导从基部到纤毛末端的顺行性蛋白质运输，而IFT-A复合物与dynein-2的复合物介导逆行的蛋白质运输。BBSome复合物将睫状膜蛋白连接到IFT机械。这种贩运机制的任何组成部分中的缺陷都会导致异常的纤毛发生和纤毛功能，并导致广泛的疾病，统称为纤毛病。在这篇综述文章中，我们概述了IFT机械组件的体系结构及其在睫状蛋白运输中的功能相互作用。