Phototransduction in Drosophila melanogaster

J Exp Biol. 2001 Oct;204(Pt 20):3403-9.

Abstract

As in most invertebrate microvillar photoreceptors, phototransduction in Drosophila melanogaster uses a G-protein-coupled phosphoinositide pathway, whereby hydrolysis of phosphatidyl inositol 4,5-bisphosphate (PIP(2)) by phospholipase C generates inositol 1,4,5-trisphosphate (InsP(3)) and diacyl glycerol (DAG), leading to activation of two classes of Ca(2+)-permeable light-sensitive channel, encoded by the trp and trpl genes. In some invertebrate photoreceptors, excitation is mediated by release of Ca(2+) from intracellular stores by InsP(3); however, in Drosophila melanogaster, recent evidence suggests instead that a lipid messenger, such as DAG, its metabolites and/or the reduction in PIP(2) levels, may mediate excitation. Like vertebrate rods, Drosophila melanogaster photoreceptors generate quantum bumps in response to single photons, but their kinetics is approximately 10-100 times faster, and this reflects a fundamentally different strategy incorporating a threshold, positive and negative feedback by Ca(2+) acting downstream of phospholipase C and a refractory period.

Publication types

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

MeSH terms

  • Animals
  • Bacterial Proteins / physiology
  • Calcium Channels / physiology
  • Calmodulin-Binding Proteins / physiology
  • DNA-Binding Proteins*
  • Drosophila Proteins*
  • Drosophila melanogaster / physiology*
  • GTP-Binding Proteins / physiology
  • Membrane Proteins / physiology
  • Phosphatidylinositol 4,5-Diphosphate / metabolism
  • Phosphatidylinositols / metabolism
  • Photoreceptor Cells / physiology
  • Signal Transduction
  • TRPC Cation Channels
  • Trans-Activators*
  • Transient Receptor Potential Channels
  • Type C Phospholipases / metabolism
  • Vision, Ocular*

Substances

  • Bacterial Proteins
  • Calcium Channels
  • Calmodulin-Binding Proteins
  • DNA-Binding Proteins
  • Drosophila Proteins
  • Membrane Proteins
  • Phosphatidylinositol 4,5-Diphosphate
  • Phosphatidylinositols
  • TRPC Cation Channels
  • Trans-Activators
  • Transient Receptor Potential Channels
  • trpl protein, Drosophila
  • Type C Phospholipases
  • GTP-Binding Proteins