The CSC is required for complete radial spoke assembly and wild-type ciliary motility

Erin E. Dymek, Thomas Heuser, Daniela Nicastro, Elizabeth F. Smith

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


The ubiquitous calcium binding protein, calmodulin (CaM), plays a major role in regulating the motility of all eukaryotic cilia and flagella. We previously identified a CaM and Spoke associated Complex (CSC) and provided evidence that this complex mediates regulatory signals between the radial spokes and dynein arms. We have now used an artificial microRNA (amiRNA) approach to reduce expression of two CSC subunits in Chlamydomonas. For all amiRNA mutants, the entire CSC is lacking or severely reduced in flagella. Structural studies of mutant axonemes revealed that assembly of radial spoke 2 is defective. Furthermore, analysis of both flagellar beating and microtubule sliding in vitro demonstrates that the CSC plays a critical role in modulating dynein activity. Our results not only indicate that the CSC is required for spoke assembly and wild-type motility, but also provide evidence for heterogeneity among the radial spokes.

Original languageEnglish (US)
Pages (from-to)2520-2531
Number of pages12
JournalMolecular biology of the cell
Issue number14
StatePublished - Jul 15 2011

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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