Phosducin regulates the expression of transducin betagamma subunits in rod photoreceptors and does not contribute to phototransduction adaptation
| Autor: | Krispel, Claudia M, Sokolov, Maxim, Chen, Yen-Ming, Song, Hongman, Herrmann, Rolf, Arshavsky, Vadim Y, Burns, Marie E |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Time Factors
genetic structures Vision Physiology Knockout Medical Physiology Dark Adaptation Inbred C57BL Phosphoproteins Heterotrimeric GTP-Binding Proteins GTP-Binding Protein alpha Subunits Membrane Potentials Mice Protein Subunits GTP-Binding Protein Regulators Retinal Rod Photoreceptor Cells Ocular Animals sense organs Transducin Phosphorylation Adaptation Eye Proteins |
| Zdroj: | The Journal of general physiology, vol 130, iss 3 |
| Popis: | For over a decade, phosducin's interaction with the betagamma 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 betagamma-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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|