Normal phototransduction in Drosophila photoreceptors lacking an InsP(3) receptor gene

Mol Cell Neurosci. 2000 May;15(5):429-45. doi: 10.1006/mcne.2000.0846.


The Drosophila light-sensitive channels TRP and TRPL are prototypical members of an ion channel family responsible for a variety of receptor-mediated Ca(2+) influx phenomena, including store-operated calcium influx. While phospholipase Cbeta is essential, downstream events leading to TRP and TRPL activation remain unclear. We investigated the role of the InsP(3) receptor (InsP(3)R) by generating mosaic eyes homozygous for a deficiency of the only known InsP(3)R gene in Drosophila. Absence of gene product was confirmed by RT-PCR, Western analysis, and immunocytochemistry. Mutant photoreceptors underwent late onset retinal degeneration; however, whole-cell recordings from young flies demonstrated that phototransduction was unaffected, quantum bumps, macroscopic responses in the presence and absence of external Ca(2+), light adaptation, and Ca(2+) release from internal stores all being normal. Using the specific TRP channel blocker La(3+) we demonstrated that both TRP and TRPL channel functions were unaffected. These results indicate that InsP(3)R-mediated store depletion does not underlie TRP and TRPL activation in Drosophila photoreceptors.

Publication types

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

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calcium Channels / genetics*
  • Calcium Channels / metabolism
  • Drosophila melanogaster / physiology*
  • Gene Deletion*
  • Homozygote
  • Immunohistochemistry
  • Inositol 1,4,5-Trisphosphate Receptors
  • Light
  • Microscopy, Electron
  • Microscopy, Electron, Scanning
  • Mutation / physiology
  • Photoreceptor Cells, Invertebrate / physiology*
  • Photoreceptor Cells, Invertebrate / radiation effects
  • Photoreceptor Cells, Invertebrate / ultrastructure
  • Receptors, Cytoplasmic and Nuclear / genetics*
  • Receptors, Cytoplasmic and Nuclear / metabolism
  • Reference Values
  • Tissue Distribution
  • Vision, Ocular / physiology*


  • Calcium Channels
  • Inositol 1,4,5-Trisphosphate Receptors
  • Receptors, Cytoplasmic and Nuclear
  • Calcium