Intraflagellar transport (IFT) cargo: IFT transports flagellar precursors to the tip and turnover products to the cell body

Due to a printer error, Figure 9 was mislabeled. The bottom-center panel should have read " HA-RSP3 " instead of " Acetylated tubulin. " The corrected figure appears below. ntraflagellar transport (IFT) is the bidirectional movement of multisubunit protein particles along axonemal micro-tubules and is required for assembly and maintenance of eukaryotic flagella and cilia. One posited role of IFT is to transport flagellar precursors to the flagellar tip for assembly. Here, we examine radial spokes, axonemal subunits consisting of 22 polypeptides, as potential cargo for IFT. Radial spokes were found to be partially assembled in the cell body, before being transported to the flagellar tip by anterograde IFT. Fully assembled radial spokes, detached I from axonemal microtubules during flagellar breakdown or turnover, are removed from flagella by retrograde IFT. Interactions between IFT particles, motors, radial spokes, and other axonemal proteins were verified by coimmuno-precipitation of these proteins from the soluble fraction of Chlamydomonas flagella. These studies indicate that one of the main roles of IFT in flagellar assembly and maintenance is to transport axonemal proteins in and out of the flagellum.