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Slowed recovery of rod photoresponse in mice lacking the GTPase accelerating protein RGS9-1.

Timely deactivation of the alpha-subunit of the rod G-protein transducin (Galphat) is essential for the temporal resolution of rod vision. Regulators of G-protein signalling (RGS) proteins accelerate hydrolysis of GTP by the alpha-subunits of heterotrimeric G proteins in vitro. Several retinal RGS proteins can act in vitro as GTPase accelerating proteins (GAP) for Galphat. Recent reconstitution experiments indicate that one of these, RGS9-1, may account for much of the Galphat GAP activity in rod outer segments (ROS). Here we report that ROS membranes from mice lacking RGS9-1 hydrolyse GTP more slowly than ROS membranes from control mice. The Gbeta5-L protein that forms a complex with RGS9-1 was absent from RGS9-/- retinas, although Gbeta5-L messenger RNA was still present. The flash responses of RGS9-/- rods rose normally, but recovered much more slowly than normal. We conclude that RGS9-1, probably in a complex with Gbeta5-L, is essential for acceleration of hydrolysis of GTP by Galphat and for normal recovery of the photoresponse.

Pubmed ID: 10676965

Authors

  • Chen CK
  • Burns ME
  • He W
  • Wensel TG
  • Baylor DA
  • Simon MI

Journal

Nature

Publication Data

February 3, 2000

Associated Grants

None

Mesh Terms

  • 3',5'-Cyclic-GMP Phosphodiesterases
  • Animals
  • Cyclic Nucleotide Phosphodiesterases, Type 6
  • GTP Phosphohydrolases
  • Guanosine Triphosphate
  • Hydrolysis
  • Mice
  • Mice, Inbred Strains
  • Mice, Knockout
  • Mice, Transgenic
  • RGS Proteins
  • Retinal Rod Photoreceptor Cells
  • Rod Cell Outer Segment
  • Transducin
  • Vision, Ocular