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Phosducin Regulates the Expression of Transducin βγ Subunits in Rod Photoreceptors and Does Not Contribute to Phototransduction Adaptation

For over a decade, phosducin's interaction with the βγ subunits of the G protein, transducin, has been thought to contribute to light adaptation by dynamically controlling the amount of transducin heterotrimer available for activation by photoexcited rhodopsin. In this study we directly tested...

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Autores principales: Krispel, Claudia M., Sokolov, Maxim, Chen, Yen-Ming, Song, Hongman, Herrmann, Rolf, Arshavsky, Vadim Y., Burns, Marie E.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2007
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2151643/
https://www.ncbi.nlm.nih.gov/pubmed/17724163
http://dx.doi.org/10.1085/jgp.200709812
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author Krispel, Claudia M.
Sokolov, Maxim
Chen, Yen-Ming
Song, Hongman
Herrmann, Rolf
Arshavsky, Vadim Y.
Burns, Marie E.
author_facet Krispel, Claudia M.
Sokolov, Maxim
Chen, Yen-Ming
Song, Hongman
Herrmann, Rolf
Arshavsky, Vadim Y.
Burns, Marie E.
author_sort Krispel, Claudia M.
collection PubMed
description For over a decade, phosducin's interaction with the βγ subunits of the G protein, transducin, has been thought to contribute to light adaptation by dynamically controlling the amount of transducin heterotrimer available for activation by photoexcited rhodopsin. In this study we directly tested this hypothesis by characterizing the dark- and light-adapted response properties of phosducin knockout (Pd−/−) rods. Pd−/− rods were notably less sensitive to light than wild-type (WT) rods. The gain of transduction, as measured by the amplification constant using the Lamb-Pugh model of activation, was 32% lower in Pd−/− rods than in WT rods. This reduced amplification correlated with a 36% reduction in the level of transducin βγ-subunit expression, and thus available heterotrimer in Pd−/− rods. However, commonly studied forms of light adaptation were normal in the absence of phosducin. Thus, phosducin does not appear to contribute to adaptation mechanisms of the outer segment by dynamically controlling heterotrimer availability, but rather is necessary for maintaining normal transducin expression and therefore normal flash sensitivity in rods.
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spelling pubmed-21516432008-03-01 Phosducin Regulates the Expression of Transducin βγ Subunits in Rod Photoreceptors and Does Not Contribute to Phototransduction Adaptation Krispel, Claudia M. Sokolov, Maxim Chen, Yen-Ming Song, Hongman Herrmann, Rolf Arshavsky, Vadim Y. Burns, Marie E. J Gen Physiol Articles For over a decade, phosducin's interaction with the βγ subunits of the G protein, transducin, has been thought to contribute to light adaptation by dynamically controlling the amount of transducin heterotrimer available for activation by photoexcited rhodopsin. In this study we directly tested this hypothesis by characterizing the dark- and light-adapted response properties of phosducin knockout (Pd−/−) rods. Pd−/− rods were notably less sensitive to light than wild-type (WT) rods. The gain of transduction, as measured by the amplification constant using the Lamb-Pugh model of activation, was 32% lower in Pd−/− rods than in WT rods. This reduced amplification correlated with a 36% reduction in the level of transducin βγ-subunit expression, and thus available heterotrimer in Pd−/− rods. However, commonly studied forms of light adaptation were normal in the absence of phosducin. Thus, phosducin does not appear to contribute to adaptation mechanisms of the outer segment by dynamically controlling heterotrimer availability, but rather is necessary for maintaining normal transducin expression and therefore normal flash sensitivity in rods. The Rockefeller University Press 2007-09 /pmc/articles/PMC2151643/ /pubmed/17724163 http://dx.doi.org/10.1085/jgp.200709812 Text en Copyright © 2007, The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Articles
Krispel, Claudia M.
Sokolov, Maxim
Chen, Yen-Ming
Song, Hongman
Herrmann, Rolf
Arshavsky, Vadim Y.
Burns, Marie E.
Phosducin Regulates the Expression of Transducin βγ Subunits in Rod Photoreceptors and Does Not Contribute to Phototransduction Adaptation
title Phosducin Regulates the Expression of Transducin βγ Subunits in Rod Photoreceptors and Does Not Contribute to Phototransduction Adaptation
title_full Phosducin Regulates the Expression of Transducin βγ Subunits in Rod Photoreceptors and Does Not Contribute to Phototransduction Adaptation
title_fullStr Phosducin Regulates the Expression of Transducin βγ Subunits in Rod Photoreceptors and Does Not Contribute to Phototransduction Adaptation
title_full_unstemmed Phosducin Regulates the Expression of Transducin βγ Subunits in Rod Photoreceptors and Does Not Contribute to Phototransduction Adaptation
title_short Phosducin Regulates the Expression of Transducin βγ Subunits in Rod Photoreceptors and Does Not Contribute to Phototransduction Adaptation
title_sort phosducin regulates the expression of transducin βγ subunits in rod photoreceptors and does not contribute to phototransduction adaptation
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2151643/
https://www.ncbi.nlm.nih.gov/pubmed/17724163
http://dx.doi.org/10.1085/jgp.200709812
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