Together, the IFT81 and IFT74 N-termini form the main module for intraflagellar transport of tubulin

J Cell Sci. 2016 May 15;129(10):2106-19. doi: 10.1242/jcs.187120. Epub 2016 Apr 11.


The assembly and maintenance of most cilia and flagella rely on intraflagellar transport (IFT). Recent in vitro studies have suggested that, together, the calponin-homology domain within the IFT81 N-terminus and the highly basic N-terminus of IFT74 form a module for IFT of tubulin. By using Chlamydomonas mutants for IFT81 and IFT74, we tested this hypothesis in vivo. Modification of the predicted tubulin-binding residues in IFT81 did not significantly affect basic anterograde IFT and length of steady-state flagella but slowed down flagellar regeneration, a phenotype similar to that seen in a strain that lacks the IFT74 N-terminus. In both mutants, the frequency of tubulin transport by IFT was greatly reduced. A double mutant that combined the modifications to IFT81 and IFT74 was able to form only very short flagella. These results indicate that, together, the IFT81 and IFT74 N-termini are crucial for flagellar assembly, and are likely to function as the main module for IFT of tubulin.

Keywords: Chlamydomonas; Cilia; Ciliary assembly; Flagella; Microtubule; Tubulin binding.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport / genetics
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Chlamydomonas reinhardtii / genetics*
  • Chlamydomonas reinhardtii / metabolism
  • Cilia / genetics
  • Cilia / metabolism
  • Flagella / genetics*
  • Flagella / metabolism
  • Phenotype
  • Protein Binding
  • Tubulin / genetics*
  • Tubulin / metabolism


  • Carrier Proteins
  • Tubulin