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R. Dallman, L. Lanberg, A. Rao, D. Chen, C.–K. Chen; The Rate–limiting Step of the Recovery of Heterozygous Rhodopsin Knockout Mouse Rods . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3737.
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Rods of heterozygous rhodopsin knockout (Rho+/–) mouse display accelerated phototransduction kinetics. We tested the hypothesis that rod recovery in these mice is rate–limited, similar to the normal animals, by transducin deactivation.
Transgenic mice overexpressing the transducin GAP complex, RGS9–1/Gß5–L/R9AP, were bred into the Rho+/– background. The dominant recovery time constant (τD) of dim flash responses was determined by double–flash ERG technique. The relative concentration of phototransduction proteins was determined by Western blotting. Retinal morphology was examined at the light microscopy level.
The τD of rods from Rho+/– animals with or without GAP over–expression were determined. Overexpressing transducin GAP accelerates the recovery of Rho+/– rods approximately 1.5 times, as compared to 2.5 times seen in the wild type background. Gross retinal morphology of 1–month old animals appears normal regardless of genetic backgrounds at the light microscope level.
Recovery from dim flashes in Rho+/– rods can be accelerated by over–expressing transducin GAP complex. The rate–limiting step of recovery in these rods is thus determined to be transducin deactivation.
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