Mechanisms of Visual Transduction

University Of California At Davis, Davis CA

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Abstract

DESCRIPTION (provided by applicant): Cone photoreceptor cells initiate vision in daytime, operating in light intensities that saturate rods and render them useless to the visual system. The ability of cones to escape saturation relies in large part upon specializations of proteins, including cone opsins, within the cone phototransduction cascade that function in synergy to preserve inward cGMP-sensitive current in strong light. During their biosynthesis, cone opsins have a surprising need for the visual chromophore, 11-cis retinal, to achieve proper folding, and our preliminary data suggests that they also possess a compensating capacity for proteolytic degradation of misfolded proteins. The proposed work will lead to a comprehensive, molecularly based account of these specializations within cones, and could be used in future work to both extend the operating range of the much more numerous rods, and develop strategies that facilitate the generation of properly folded opsins or increase the capacity to degrade misfolded opsins.