Molecular basis of amplification in Drosophila phototransduction: roles for G protein, phospholipase C, and diacylglycerol kinase

Neuron. 2002 Nov 14;36(4):689-701. doi: 10.1016/s0896-6273(02)01048-6.


In Drosophila photoreceptors, the amplification responsible for generating quantum bumps in response to photoisomerization of single rhodopsin molecules has been thought to be mediated downstream of phospholipase C (PLC), since bump amplitudes were reportedly unaffected in mutants with greatly reduced levels of either G protein or PLC. We now find that quantum bumps in such mutants are reduced approximately 3- to 5-fold but are restored to near wild-type values by mutations in the rdgA gene encoding diacylglycerol kinase (DGK) and also by depleting intracellular ATP. The results demonstrate that amplification requires activation of multiple G protein and PLC molecules, identify DGK as a key enzyme regulating amplification, and implicate diacylglycerol as a messenger of excitation in Drosophila phototransduction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / genetics
  • Adenosine Triphosphate / metabolism
  • Animals
  • Dark Adaptation / genetics
  • Diacylglycerol Kinase / genetics*
  • Down-Regulation / genetics
  • Drosophila melanogaster / enzymology*
  • Drosophila melanogaster / genetics
  • Fungal Proteins / genetics
  • GTP-Binding Protein alpha Subunits, Gq-G11
  • GTP-Binding Proteins / genetics*
  • Heterotrimeric GTP-Binding Proteins / genetics
  • Heterotrimeric GTP-Binding Proteins / metabolism
  • Membrane Potentials / genetics
  • Mutation / genetics
  • Phosphatidylinositol Diacylglycerol-Lyase
  • Photoreceptor Cells, Invertebrate / cytology
  • Photoreceptor Cells, Invertebrate / enzymology*
  • Rhodopsin / genetics
  • Saccharomyces cerevisiae Proteins*
  • Sensory Thresholds / physiology
  • Transcription Factors / deficiency
  • Transcription Factors / genetics
  • Type C Phospholipases / deficiency
  • Type C Phospholipases / genetics*
  • Vision, Ocular / genetics*


  • Fungal Proteins
  • PIP2 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • Adenosine Triphosphate
  • Rhodopsin
  • Diacylglycerol Kinase
  • Type C Phospholipases
  • GTP-Binding Proteins
  • GTP-Binding Protein alpha Subunits, Gq-G11
  • Heterotrimeric GTP-Binding Proteins
  • Phosphatidylinositol Diacylglycerol-Lyase