Oxyopia Abstract

August 9, 2002
Noon
489 Minor Hall

Marie Burns, PhD
Center for Neuroscience, Department Psychiatry, University of California, Davis
Host: John Flannery

Title

"Deactivation mechanisms of rod phototransduction"

Abstract

Suction electrode recording from rod outer segments, developed more than 20 years ago by Baylor, Lamb, and Yau (1979), is an ideal method for monitoring phototransduction in intact rods under physiological conditions. In recent years, we have combined suction electrode recording with biochemical and gene targeting techniques to define the molecular mechanisms that regulate phototransduction in mouse rods. Our experiments have shown that rhodopsin deactivation requires multiple phosphorylation by rhodopsin kinase, followed by arrestin binding. Our experiments on G protein deactivation have shown that GTP hydrolysis by transducin is catalyzed by RGS9-Gb5L preferentially when transducin is bound to PDE. Finally, calcium feedback to guanylate cyclase has a profound impact on the temporal properties of the single photon response, the rod's signal-to-noise ratio and it's ability to adapt to steady light. Thus, the mechanisms that define the characteristic amplitude and kinetics of the light responses for rods are highly regulated, and likely are mimicked by other G protein cascades in neurons with strict temporal requirements.

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