Visual transduction begins with the absorption of a photon by rhodopsin. Photoisomerization of the chromophore, from 11-cis-retinal to all-trans-retinal, must somehow signal the photoreceptor synapse to alter its release of transmitter onto second-order neurons. This signal is produced by the cyclic GMP-gated ion channel, a protein that regulates the voltage across the membrane in rods and cones. This ion channel, then, converts the signal of light into an electrical signal the brain can understand. This proposal focuses on the cGMP-gated ion channels, their role in phototransduction, their modulation by physiological stimuli, and the molecular mechanism by which cGMP binding leads to opening of the ion-conducting pore. We will examine the different components of the cGMP-gated ion channel protein to determine how they come together and how they interact. As a dynamic protein molecule whose structure and function change according to light levels, changes in interactions between parts of this protein are critical in allowing it to perform its job in vision. We will use the following tools to study how this protein works: electrical recordings, to assay the flux of charged ions through the pore of the protein; molecular biology to alter the amino acid sequence of the protein and test specific models of its function; and biochemical assays to study interactions between different parts of domains of the protein. Through these experiments we expect to gain significant insight into how the cGMP-gated ion channels function during visual transduction.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY013007-07
Application #
6944726
Study Section
Neurotransporters, Receptors, and Calcium Signaling Study Section (NTRC)
Program Officer
Mariani, Andrew P
Project Start
1999-08-06
Project End
2007-08-31
Budget Start
2005-09-01
Budget End
2006-08-31
Support Year
7
Fiscal Year
2005
Total Cost
$379,000
Indirect Cost
Name
University of Washington
Department
Physiology
Type
Schools of Medicine
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
Collins, Marcus D; Gordon, Sharona E (2013) Short-chain phosphoinositide partitioning into plasma membrane models. Biophys J 105:2485-94
Portet, Thomas; Gordon, Sharona E; Keller, Sarah L (2012) Increasing membrane tension decreases miscibility temperatures; an experimental demonstration via micropipette aspiration. Biophys J 103:L35-7
Stein, Alexander T; Ufret-Vincenty, Carmen A; Hua, Li et al. (2006) Phosphoinositide 3-kinase binds to TRPV1 and mediates NGF-stimulated TRPV1 trafficking to the plasma membrane. J Gen Physiol 128:509-22
Hua, Li; Gordon, Sharona E (2005) Functional interactions between A' helices in the C-linker of open CNG channels. J Gen Physiol 125:335-44
Rosenbaum, Tamara; Gordon-Shaag, Ariela; Islas, Leon D et al. (2004) State-dependent block of CNG channels by dequalinium. J Gen Physiol 123:295-304
Rosenbaum, Tamara; Islas, Leon D; Carlson, Anne E et al. (2003) Dequalinium: a novel, high-affinity blocker of CNGA1 channels. J Gen Physiol 121:37-47
Rosenbaum, Tamara; Gordon, Sharona E (2002) Dissecting intersubunit contacts in cyclic nucleotide-gated ion channels. Neuron 33:703-13
Richards, M J; Gordon, S E (2000) Cooperativity and cooperation in cyclic nucleotide-gated ion channels. Biochemistry 39:14003-11