Single-molecule biophysics research group

University of California, Berkeley


Intraflagellar Transport and Motility


We use intraflagellar transport (IFT) in Chlamydomonas as a model system to elucidate how cargoes are transported in vivo. So far, we have tracked flagellar membrane glycoproteins (FMG1-B) and observed that these proteins are transported by IFT. Through FMG1-B, IFT powers and regulates both bead and gliding motility. By using this system, we aim to understand how opposite polarity motors function together to move cargoes bidirectionally along the microtubules and how cells control their activity by associated enzymes. We use mutated strains of Chlamydomonas to externally control motor activity and manipulate cargo transport by applying forces via optical tweezers. Our studies will reveal how cells can rapidly grow and maintain cilia and flagella.

IFT fig 1

Figure 1. Model of gliding. A retrograde IFT train (blue) attach to the glass surface through flagellar membrane glycoproteins (yellow) and drive the cell body forward in a manner similar to microtubule gliding assays.

Fig. 2

Figure 2. An antibody-coated bead connected to an IFT train through transmembrane proteins was trapped by a focused laser beam for force measurements. An IFT train imaged by fluorescence microscopy (top) colocalized with the bead (bottom), showing that the external force did not disrupt the bead-IFT connection.

  Relevant papers
  • Sheng-Min Shih, Benjamin D Engel, Fatih Kocabas, Thomas Bilyard, Arne Gennerich, and Wallace F Marshall. Intraflagellar transport drives flagellar surface motility. 2013. eLife 2013;2:e00744. pdf