Chlamydomonas reinhardtii hydin is a central pair protein required for flagellar motility

J Cell Biol. 2007 Feb 12;176(4):473-82. doi: 10.1083/jcb.200611115.


Mutations in Hydin cause hydrocephalus in mice, and HYDIN is a strong candidate for causing hydrocephalus in humans. The gene is conserved in ciliated species, including Chlamydomonas reinhardtii. An antibody raised against C. reinhardtii hydin was specific for an approximately 540-kD flagellar protein that is missing from axonemes of strains that lack the central pair (CP). The antibody specifically decorated the C2 microtubule of the CP apparatus. An 80% knock down of hydin resulted in short flagella lacking the C2b projection of the C2 microtubule; the flagella were arrested at the switch points between the effective and recovery strokes. Biochemical analyses revealed that hydin interacts with the CP proteins CPC1 and kinesin-like protein 1 (KLP1). In conclusion, C. reinhardtii hydin is a CP protein required for flagellar motility and probably involved in the CP-radial spoke control pathway that regulates dynein arm activity. Hydrocephalus caused by mutations in hydin likely involves the malfunctioning of cilia because of a defect in the CP.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chlamydomonas reinhardtii / metabolism*
  • Chlamydomonas reinhardtii / ultrastructure
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Down-Regulation / physiology
  • Flagella / metabolism*
  • Flagella / ultrastructure
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Hydrocephalus / genetics
  • Hydrocephalus / metabolism
  • Hydrocephalus / physiopathology
  • Locomotion / physiology*
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Microtubules / metabolism*
  • Microtubules / ultrastructure
  • Mutation / genetics
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism*


  • DNA-Binding Proteins
  • Fungal Proteins
  • Hydin protein, mouse
  • Microfilament Proteins
  • Microtubule-Associated Proteins
  • Protozoan Proteins
  • kinesin-like protein 1