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Published February 3, 2000 | public
Journal Article

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


Timely deactivation of the ɑ-subunit of the rod G-protein transducin (Gɑt) is essential for the temporal resolution of rod vision. Regulators of G-protein signalling (RGS) proteins accelerate hydrolysis of GTP by the ɑ-subunits of heterotrimeric G proteins in vitro. Several retinal RGS proteins can act in vitro as GTPase accelerating proteins (GAP) for Gɑt. Recent reconstitution experiments indicate that one of these, RGS9-1, may account for much of the Gɑt 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 Gβ5-L protein that forms a complex with RGS9-1 (ref. 10) was absent from RGS9-/- retinas, although Gβ5-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 Gβ5-L, is essential for acceleration of hydrolysis of GTP by Gɑt and for normal recovery of the photoresponse.

Additional Information

© 2000 Macmillan Magazines Ltd. Received 5 October 1999; Accepted 24 November 1999. We thank members of the Caltech Transgenic Core Facility for their technical support, and R. Lefkowitz, J. Hurley and H. Jurgen-Fuller for antibodies. This work was supported by grants from the NIH.

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