The light response of ON bipolar neurons requires G[alpha]o

J Neurosci. 2000 Dec 15;20(24):9053-8. doi: 10.1523/JNEUROSCI.20-24-09053.2000.


ON bipolar neurons in retina detect the glutamate released by rods and cones via metabotropic glutamate receptor 6 (mGluR6), whose cascade is unknown. The trimeric G-protein G(o) might mediate this cascade because it colocalizes with mGluR6. To test this, we studied the retina in mice negative for the alpha subunit of G(o) (Galpha(o)-/-). Retinal layering, key cell types, synaptic structure, and mGluR6 expression were all normal, as was the a-wave of the electroretinogram, which represents the rod and cone photocurrents. However, the b-wave of the electroretinogram, both rod- and cone-driven components, was entirely missing. Because the b-wave represents the massed response of ON bipolar cells, its loss in the Galpha(o) null mouse establishes that the light response of the ON bipolar cell requires G(o). This represents the first function to be defined in vivo for the alpha subunit of the most abundant G-protein of the brain.

Publication types

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

MeSH terms

  • Animals
  • Antigens, Differentiation / metabolism
  • Electroretinography
  • Heterotrimeric GTP-Binding Proteins / deficiency
  • Heterotrimeric GTP-Binding Proteins / genetics
  • Heterotrimeric GTP-Binding Proteins / metabolism*
  • Mice
  • Mice, Knockout
  • Neurons / cytology
  • Neurons / metabolism*
  • Photic Stimulation*
  • Protein Isoforms / deficiency
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Retina / cytology
  • Retina / metabolism*
  • Retinal Cone Photoreceptor Cells / cytology
  • Retinal Cone Photoreceptor Cells / metabolism
  • Retinal Rod Photoreceptor Cells / cytology
  • Retinal Rod Photoreceptor Cells / metabolism
  • Second Messenger Systems / physiology
  • Synapses / metabolism
  • Synapses / ultrastructure


  • Antigens, Differentiation
  • Protein Isoforms
  • Heterotrimeric GTP-Binding Proteins