We propose to study visual transduction as """"""""a nerve signal in a test tube"""""""" by utilizing purified suspensions of frog outer segments still attached to their mitochondria rich inner segments (OS-IS). Our development of such a peparation permits us to simultaneously assay and compare ion fluxes and biochemical changes accompanying excitation and adaptation in a chemically defined preparation, experiments of a sort that are not yet possible in other nerve membrane preparations. We plan to: 1. Characterize the processes of light adaptation, recovery from large rhodopsin bleaches in the dark, and quantum bump membrane noise, determining whether they correlate with simultaneous light-induced changes in the concentration or binding state of nucleotides or other small molecules, or with covalent protein modifications such as phosphorylation. 2. Begin a serarch for new putative intracellular messengers by systematically surveying light-induced changes in the concentration or binding of small organic molecules and proteins. 3. Develop an in vitro assay for the light-sensitive conductance that can be used to define the necessary components of the transduction mechanism and also to screen putative conductance regulators. The experimental approaches being used in this work and the mechanisms being elucidated are relevant to understanding events intervening between input and output in many other cellular systems. Such understanding is especially relevant to defining the perturbations underlying diseased states of the retina, and permits a more rational approach to appropriate thereapy.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY000463-22
Application #
3255391
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1978-03-01
Project End
1991-01-31
Budget Start
1990-02-01
Budget End
1991-01-31
Support Year
22
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Wisconsin Madison
Department
Type
Other Domestic Higher Education
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
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Klenchin, V A; Calvert, P D; Bownds, M D (1995) Inhibition of rhodopsin kinase by recoverin. Further evidence for a negative feedback system in phototransduction. J Biol Chem 270:16147-52
Calvert, P D; Klenchin, V A; Bownds, M D (1995) Rhodopsin kinase inhibition by recoverin. Function of recoverin myristoylation. J Biol Chem 270:24127-9
Slepak, V Z; Artemyev, N O; Zhu, Y et al. (1995) An effector site that stimulates G-protein GTPase in photoreceptors. J Biol Chem 270:14319-24
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Cote, R H; Bownds, M D; Arshavsky, V Y (1994) cGMP binding sites on photoreceptor phosphodiesterase: role in feedback regulation of visual transduction. Proc Natl Acad Sci U S A 91:4845-9
Arshavsky, V Y; Dumke, C L; Zhu, Y et al. (1994) Regulation of transducin GTPase activity in bovine rod outer segments. J Biol Chem 269:19882-7
Arshavsky, V Y; Dumke, C L; Bownds, M D (1992) Noncatalytic cGMP-binding sites of amphibian rod cGMP phosphodiesterase control interaction with its inhibitory gamma-subunits. A putative regulatory mechanism of the rod photoresponse. J Biol Chem 267:24501-7
Arshavsky VYu; Gray-Keller, M P; Bownds, M D (1991) cGMP suppresses GTPase activity of a portion of transducin equimolar to phosphodiesterase in frog rod outer segments. Light-induced cGMP decreases as a putative feedback mechanism of the photoresponse. J Biol Chem 266:18530-7

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