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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...
Autores principales: | , , , , , , |
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Formato: | Texto |
Lenguaje: | English |
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The Rockefeller University Press
2007
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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. |
format | Text |
id | pubmed-2151643 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2007 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
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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