Calnexin is essential for rhodopsin maturation, Ca2+ regulation, and photoreceptor cell survival

Neuron. 2006 Jan 19;49(2):229-41. doi: 10.1016/j.neuron.2005.12.011.


In sensory neurons, successful maturation of signaling molecules and regulation of Ca2+ are essential for cell function and survival. Here, we demonstrate a multifunctional role for calnexin as both a molecular chaperone uniquely required for rhodopsin maturation and a regulator of Ca2+ that enters photoreceptor cells during light stimulation. Mutations in Drosophila calnexin lead to severe defects in rhodopsin (Rh1) expression, whereas other photoreceptor cell proteins are expressed normally. Mutations in calnexin also impair the ability of photoreceptor cells to control cytosolic Ca2+ levels following activation of the light-sensitive TRP channels. Finally, mutations in calnexin lead to retinal degeneration that is enhanced by light, suggesting that calnexin's function as a Ca2+ buffer is important for photoreceptor cell survival. Our results illustrate a critical role for calnexin in Rh1 maturation and Ca2+ regulation and provide genetic evidence that defects in calnexin lead to retinal degeneration.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Animals, Genetically Modified
  • Blotting, Northern
  • Calcium / metabolism
  • Calcium Signaling / physiology*
  • Calnexin / physiology*
  • Cell Survival / physiology
  • Chromatography, Affinity
  • DNA / biosynthesis
  • DNA / genetics
  • Drosophila
  • Electrophoresis, Polyacrylamide Gel
  • Immunohistochemistry
  • Light
  • Microscopy, Electron
  • Molecular Chaperones
  • Molecular Sequence Data
  • Mutation / genetics
  • Mutation / physiology
  • Patch-Clamp Techniques
  • Photoreceptor Cells, Invertebrate / cytology
  • Photoreceptor Cells, Invertebrate / physiology*
  • Retinal Degeneration / genetics
  • Retinal Degeneration / pathology
  • Rhodopsin / biosynthesis
  • Rhodopsin / genetics
  • Rhodopsin / physiology*


  • Molecular Chaperones
  • Calnexin
  • DNA
  • Rhodopsin
  • Calcium