Protein particles in Chlamydomonas flagella undergo a transport cycle consisting of four phases

Carlo Iomini, Veronica Babaev-Khaimov, Massimo Sassaroli, Gianni Piperno

Research output: Contribution to journalArticlepeer-review

169 Scopus citations


We used an improved procedure to analyze the intraflagellar transport (IFT) of protein particles in Chlamydomonas and found that the frequency of the particles, not only the velocity, changes at each end of the flagella. Thus, particles undergo structural remodeling at both flagellar locations. Therefore, we propose that the IFT consists of a cycle composed of at least four phases: phases II and IV, in which particles undergo anterograde and retrograde transport, respectively, and phases I and III, in which particles are remodeled/ exchanged at the proximal and distal end of the flagellum, respectively. In support of our model, we also identified 13 distinct mutants of flagellar assembly (fla), each defective in one or two consecutive phases of the IFT cycle. The phase I-II mutant fla10-1 revealed that cytoplasmic dynein requires the function of kinesin II to participate in the cycle. Phase I and II mutants accumulate complex A, a particle component, near the basal bodies. In contrast, phase III and IV mutants accumulate complex B, a second particle component, in flagellar bulges. Thus, fla mutations affect the function of each complex at different phases of the cycle.

Original languageEnglish (US)
Pages (from-to)13-24
Number of pages12
JournalJournal of Cell Biology
Issue number1
StatePublished - Apr 2 2001
Externally publishedYes


  • Chlamydomonas
  • Intraflagellar transport
  • Kinesin II
  • Temperature-sensitive mutants
  • Transport cycle

ASJC Scopus subject areas

  • Cell Biology


Dive into the research topics of 'Protein particles in Chlamydomonas flagella undergo a transport cycle consisting of four phases'. Together they form a unique fingerprint.

Cite this