An eye-specific G beta subunit essential for termination of the phototransduction cascade

Nature. 1994 Jul 7;370(6484):59-61. doi: 10.1038/370059a0.


Heterotrimeric G proteins couple various receptors to intracellular effector molecules. Although the role of the G alpha subunit in effector activation, guanine nucleotide exchange and GTP hydrolysis has been well studied, the cellular functions of the G beta subunits are less well understood. G beta gamma dimers bind G alpha subunits and anchor them to the membrane for presentation to the receptor. In specific systems, the G beta subunits have also been implicated in direct coupling to ion channels and to effector molecules. We have isolated Drosophila melanogaster mutants defective in an eye-specific G-protein beta-subunit (G beta e), and show here that the beta-subunit is essential for G-protein-receptor coupling in vivo. Remarkably, G beta mutants are also severely defective in the deactivation of the light response, demonstrating an essential role for the G beta subunit in terminating the active state of this signalling cascade.

Publication types

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

MeSH terms

  • Animals
  • Calcium / metabolism
  • Drosophila melanogaster
  • Electrophysiology
  • Eye / metabolism*
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism*
  • In Vitro Techniques
  • Kinetics
  • Light
  • Mutation
  • Neural Conduction*
  • Photoreceptor Cells, Invertebrate / metabolism*
  • Rhodopsin / metabolism


  • Rhodopsin
  • GTP-Binding Proteins
  • Calcium