The retina converts light into an electrical signal through a series of biochemical steps collectively referred to as phototransduction. This signal is eventually relayed to the visual cortex of the brain, where visual perception occurs. Photoreceptor cells are able to respond to light throughout our lives because they have the ability to regenerate proteins as well as a light-sensitive chromophore. The long-term objective of our research is to elucidate the molecular reactions involved in phototransduction, including those directly involved in the regenerative capability of photoreceptor cells. Phototransduction serves as a prototype for a multitude of G protein-mediated signal transduction events initiated by activation of G protein-coupled receptors (GPCRs) and thus understanding of this process is broadly applicable to other signal transduction cascades. Our continuing investigation of phototransduction will focus on selected proteins in this pathway. Mutations in the genes encoding these particular proteins are among the main causes of blinding diseases in humans. We propose three thematically linked specific aims in this application: (1) Determine the structures of phototransduction-specific proteins and their regulation by posttranslational modifications. Understanding the 3-dimensional architecture of transduction proteins and their posttranslational modifications will yield an unparalleled wealth of atomic detail related to their function. (2) Elucidate the structural/biophysical changes involved in rhodopsin activation. Studies proposed herein will provide new biochemical and physiological insights into critical events required for receptor activation and contribute to our understanding of GPCR signaling. (3) Use pathogenic mutations of rhodopsin to determine precisely how changes in its structure affect the viability of rod photoreceptor cells. By elucidating the molecular details of abnormal cellular processing of mutated rhodopsin, we will better understand the ensuing pathology as well as develop a rational approach to alleviate retinal dystrophies related to mutations in the opsin gene.

Public Health Relevance

/ STATEMENT Phototransduction serves as a model for a multitude of G-protein-mediated signal transduction pathways initiated by activation of G-protein coupled receptors (GPCRs). Thus a more rigorous understanding of this process will have broad application to other signal transduction cascades. Therefore, the long-term objective of our research is to elucidate the detailed molecular events involved in phototransduction.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
3R01EY008061-27S1
Application #
8791774
Study Section
Biology and Diseases of the Posterior Eye Study Section (BDPE)
Program Officer
Neuhold, Lisa
Project Start
1990-02-01
Project End
2014-06-30
Budget Start
2014-01-01
Budget End
2014-06-30
Support Year
27
Fiscal Year
2014
Total Cost
$334,212
Indirect Cost
$120,519
Name
Case Western Reserve University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
077758407
City
Cleveland
State
OH
Country
United States
Zip Code
44106
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Tian, Mei; Zallocchi, Marisa; Wang, Weimin et al. (2013) Light-induced translocation of RGS9-1 and G?5L in mouse rod photoreceptors. PLoS One 8:e58832

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