Follit John A, Tuft Richard A, Fogarty Kevin E, Pazour Gregory J
Program in Molecular Medicine, Department of Physiology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
Mol Biol Cell. 2006 Sep;17(9):3781-92. doi: 10.1091/mbc.e06-02-0133. Epub 2006 Jun 14.
Eukaryotic cilia are assembled via intraflagellar transport (IFT) in which large protein particles are motored along ciliary microtubules. The IFT particles are composed of at least 17 polypeptides that are thought to contain binding sites for various cargos that need to be transported from their site of synthesis in the cell body to the site of assembly in the cilium. We show here that the IFT20 subunit of the particle is localized to the Golgi complex in addition to the basal body and cilia where all previous IFT particle proteins had been found. In living cells, fluorescently tagged IFT20 is highly dynamic and moves between the Golgi complex and the cilium as well as along ciliary microtubules. Strong knock down of IFT20 in mammalian cells blocks ciliary assembly but does not affect Golgi structure. Moderate knockdown does not block cilia assembly but reduces the amount of polycystin-2 that is localized to the cilia. This work suggests that IFT20 functions in the delivery of ciliary membrane proteins from the Golgi complex to the cilium.
真核生物纤毛通过鞭毛内运输（IFT）组装而成，在该过程中，大型蛋白质颗粒沿纤毛微管移动。IFT颗粒由至少17种多肽组成，这些多肽被认为含有各种货物的结合位点，这些货物需要从细胞体中的合成位点运输到纤毛中的组装位点。我们在此表明，除了先前发现所有IFT颗粒蛋白的基体和纤毛外，该颗粒的IFT20亚基还定位于高尔基体复合体。在活细胞中，荧光标记的IFT20高度动态，在高尔基体复合体和纤毛之间以及沿纤毛微管移动。在哺乳动物细胞中强烈敲低IFT20会阻止纤毛组装，但不影响高尔基体结构。适度敲低不会阻止纤毛组装，但会减少定位于纤毛的多囊蛋白-2的量。这项工作表明，IFT20在将纤毛膜蛋白从高尔基体复合体运输到纤毛的过程中发挥作用。
