The overall objective of this proposal is to understand molecular mechanisms that govern the duration of G protein signaling in photoreceptor cells. The photoreceptor G protein, transducin, plays a central role in vertebrate phototransduction where it conveys a signal from the activated receptor, photoexcited rhodopsin, to its effector, cGMP phosphodiesterase. Transducin is activated when photoexcited rhodopsin catalyses an exchange of GDP for GTP on the transducin alpha subunit and continues to stimulate PDE activity until the bound GTP is hydrolyzed. Studies conducted by this and other laboratories have shown that photoreceptors contain a multi-protein complex, which accelerates the slow intrinsic GTPase activity of transducin to a rate sufficient for timely photoresponse recovery. This complex includes the ninth member of the Regulators of G protein Signaling protein family (RGS9-1), type 5 G protein beta-subunit (Gbeta5L) and their membrane anchor (R9AP). Understanding the exact molecular mechanisms by which members of this protein ensemble contribute to the activation of transducin GTPase in a highly coordinated manner is the major goal of this proposal.
Aim 1 is to establish the mechanism by which R9AP potentiates the ability of the entire complex to activate transducin GTPase.
Aim 2 is to understand the nature of protein-protein interactions between RGS9-1, Gbeta5L and R9AP.
Aim 3 is to search for additional proteins interacting with the components of the GTPase activating complex in photoreceptors.
Aim 4 is to study phototransduction in rods from the animals where the content or composition of the GTPase activating complex is genetically modified. Addressing this problem is important not only for the understanding of the molecular mechanism of photoresponse recovery, but also for establishing general molecular principles of signal duration regulation in other intracellular signaling pathways. This work is relevant to understanding of how biochemical pathways responsible for ensuring normal photoreceptor activity may be affected in various inherited eye diseases.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-SSS-U (03))
Program Officer
Mariani, Andrew P
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Duke University
Schools of Medicine
United States
Zip Code
Sharif, Ali S; Yu, Dongmei; Loertscher, Stuart et al. (2018) C8ORF37 Is Required for Photoreceptor Outer Segment Disc Morphogenesis by Maintaining Outer Segment Membrane Protein Homeostasis. J Neurosci 38:3160-3176
Salinas, Raquel Y; Pearring, Jillian N; Ding, Jin-Dong et al. (2017) Photoreceptor discs form through peripherin-dependent suppression of ciliary ectosome release. J Cell Biol 216:1489-1499
Pearring, Jillian N; San Agustin, Jovenal T; Lobanova, Ekaterina S et al. (2017) Loss of Arf4 causes severe degeneration of the exocrine pancreas but not cystic kidney disease or retinal degeneration. PLoS Genet 13:e1006740
Spencer, William J; Pearring, Jillian N; Salinas, Raquel Y et al. (2016) Progressive Rod-Cone Degeneration (PRCD) Protein Requires N-Terminal S-Acylation and Rhodopsin Binding for Photoreceptor Outer Segment Localization and Maintaining Intracellular Stability. Biochemistry 55:5028-37
Ploier, Birgit; Caro, Lydia N; Morizumi, Takefumi et al. (2016) Dimerization deficiency of enigmatic retinitis pigmentosa-linked rhodopsin mutants. Nat Commun 7:12832
Ding, Jin-Dong; Salinas, Raquel Y; Arshavsky, Vadim Y (2015) Discs of mammalian rod photoreceptors form through the membrane evagination mechanism. J Cell Biol 211:495-502
Pearring, Jillian N; Spencer, William J; Lieu, Eric C et al. (2015) Guanylate cyclase 1 relies on rhodopsin for intracellular stability and ciliary trafficking. Elife 4:
Pearring, Jillian N; Lieu, Eric C; Winter, Joan R et al. (2014) R9AP targeting to rod outer segments is independent of rhodopsin and is guided by the SNARE homology domain. Mol Biol Cell 25:2644-9
Srinivasan, Pratul P; Heflin, Stephanie J; Izatt, Joseph A et al. (2014) Automatic segmentation of up to ten layer boundaries in SD-OCT images of the mouse retina with and without missing layers due to pathology. Biomed Opt Express 5:348-65
Arshavsky, Vadim Y; Burns, Marie E (2014) Current understanding of signal amplification in phototransduction. Cell Logist 4:e29390

Showing the most recent 10 out of 41 publications