The Chlamydomonas PF6 Locus Encodes a Large alanine/proline-rich Polypeptide That Is Required for Assembly of a Central Pair Projection and Regulates Flagellar Motility

Mol Biol Cell. 2001 Mar;12(3):739-51. doi: 10.1091/mbc.12.3.739.


Efficient motility of the eukaryotic flagellum requires precise temporal and spatial control of its constituent dynein motors. The central pair and its associated structures have been implicated as important members of a signal transduction cascade that ultimately regulates dynein arm activity. To identify central pair components involved in this process, we characterized a Chlamydomonas motility mutant (pf6-2) obtained by insertional mutagenesis. pf6-2 flagella twitch ineffectively and lack the 1a projection on the C1 microtubule of the central pair. Transformation with constructs containing a full-length, wild-type copy of the PF6 gene rescues the functional, structural, and biochemical defects associated with the pf6 mutation. Sequence analysis indicates that the PF6 gene encodes a large polypeptide that contains numerous alanine-rich, proline-rich, and basic domains and has limited homology to an expressed sequence tag derived from a human testis cDNA library. Biochemical analysis of an epitope-tagged PF6 construct demonstrates that the PF6 polypeptide is an axonemal component that cosediments at 12.6S with several other polypeptides. The PF6 protein appears to be an essential component required for assembly of some of these polypeptides into the C1-1a projection.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Algal Proteins*
  • Alleles
  • Amino Acid Sequence
  • Animals
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / physiology*
  • Chlamydomonas / genetics*
  • Chlamydomonas / physiology*
  • Chlamydomonas / ultrastructure
  • Flagella / physiology*
  • Flagella / ultrastructure
  • Genes, Protozoan
  • Humans
  • Male
  • Microscopy, Electron
  • Molecular Sequence Data
  • Movement
  • Mutagenesis, Insertional
  • Protozoan Proteins / chemistry
  • Protozoan Proteins / genetics*
  • Protozoan Proteins / physiology*
  • Sequence Homology, Amino Acid


  • Algal Proteins
  • Bacterial Proteins
  • Protozoan Proteins

Associated data

  • GENBANK/AF327876