The phosphorylation state of an aurora-like kinase marks the length of growing flagella in Chlamydomonas

Minna Luo, Muqing Cao, Yinan Kan, Guihua Li, William Snell, Junmin Pan

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


Flagella and cilia are structurally polarized organelles whose lengths are precisely defined, and alterations in length are related to several human disorders [1, 2]. Intraflagellar transport (IFT) and protein signaling molecules are implicated in specifying flagellar and ciliary length [3-6], but evidence has been lacking for a flagellum and cilium length sensor that could participate in active length control or establishment of structural polarity. Previously, we showed that the phosphorylation state of the aurora-like protein kinase CALK in Chlamydomonas is a marker of the absence of flagella. Here we show that CALK phosphorylation state is also a marker for flagellar length. CALK is phosphorylated in cells without flagella, and during flagellar assembly it becomes dephosphorylated. Dephosphorylation is not simply a consequence of initiation of flagellar assembly or of time after experimentally induced flagellar loss, but instead requires flagella to be assembled to a threshold length. Analysis of cells with flagella of varying lengths shows that the threshold length for CALK dephosphorylation is ∼6 μm (half length). Studies with short and long flagellar mutants indicate that cells detect absolute rather than relative flagellar length. Our results demonstrate that cells possess a mechanism for translating flagellar length into a posttranslational modification of a known flagellar regulatory protein.

Original languageEnglish (US)
Pages (from-to)586-591
Number of pages6
JournalCurrent Biology
Issue number7
StatePublished - Apr 12 2011

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Neuroscience(all)


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