Translocation of Gqα mediates long-term adaptation in Drosophila photoreceptors

Shahar Frechter, Natalie Elia, Vered Tzarfaty, Zvi Selinger, Baruch Minke

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Light adaptation is a process that enables photoreceptor cells to operate over a wide range of light intensities without saturation. In invertebrate photoreceptors, fast adaptation is mediated by a Ca2+-dependent negative-feedback mechanism, which mainly affects the terminal steps of the cascade. Therefore, the response to each photon is smaller as light intensity increases, accommodating both high sensitivity and a vast dynamic range. Here, we describe a novel type of adaptation, which is mediated by one of the first steps in the phototransduction cascade affecting the sensitivity to absorbed photons. Long exposure to light resulted in dramatic reduction in the probability of each absorbed photon to elicit a response, whereas the size and shape of each single photon response did not change. To dissect the molecular mechanism underlying this form of adaptation we used a series of Drosophila mutants. Genetic dissection showed a pivotal role for light-induced translocation of Gqα between the signaling membrane and the cytosol. Biochemical studies revealed that the sensitivity to light depends on membrane Gqα concentration, which was modulated either by light or by mutations that impaired its targeting to the membrane. We conclude that long-term adaptation is mediated by the movement of Gqα from the signaling membrane to the cytosol, thereby reducing the probability of each photon to elicit a response. The slow time scale of this adaptation fits well with day/night light intensity changes, because there is no need to maintain single photon sensitivity during daytime.

Original languageEnglish
Pages (from-to)5571-5583
Number of pages13
JournalJournal of Neuroscience
Issue number21
StatePublished - 23 May 2007
Externally publishedYes


  • Drosophila mutants
  • Heterotrimeric G protein
  • Light adaptation
  • Phototransduction
  • Protein translocation
  • Quantum bumps

ASJC Scopus subject areas

  • Neuroscience (all)


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