Light-modulated subcellular localization of the alpha-subunit of GTP-binding protein Gq in crayfish photoreceptors

Vis Neurosci. May-Jun 1996;13(3):539-47. doi: 10.1017/s095252380000821x.


Gq-type GTP-binding protein (Gq) plays an important role in invertebrate visual phototransduction. The subcellular localization of the alpha subunit of visual Gq in crayfish photoreceptor was investigated immunocytochemically and biochemically to demonstrate the details of the rhodopsin-Gq interaction. The localization of Gq(alpha) changed depending on the light condition. In the dark, Gq(alpha) was localized in the whole rhabdoms as the membrane-bound form. In the light, half of the Gq(alpha) was localized in the cytoplasm as the soluble form. The translocation of Gq(alpha) was reversible. The light-modulated translocation possibly controls the amount of Gq that can be activated by rhodopsin. In vitro hydroxylamine treatment of rhabdomeric membranes suggested that the translocation was regulated by the fatty-acid modification of Gq(alpha).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Ocular / physiology
  • Animals
  • Astacoidea / metabolism*
  • Dark Adaptation / physiology
  • Electrophoresis, Polyacrylamide Gel
  • Fatty Acids / metabolism
  • GTP-Binding Proteins / metabolism*
  • Hydroxylamine
  • Hydroxylamines / pharmacology
  • Immunoblotting
  • Immunohistochemistry
  • Light*
  • Microscopy, Immunoelectron
  • Photoreceptor Cells, Invertebrate / metabolism*
  • Photoreceptor Cells, Invertebrate / radiation effects*
  • Subcellular Fractions / metabolism*
  • Tissue Distribution / drug effects
  • Tissue Distribution / radiation effects


  • Fatty Acids
  • Hydroxylamines
  • Hydroxylamine
  • GTP-Binding Proteins