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You-Wei Peng, Mei Tian, Marisa Zallocchi, Weimin Wang, Ching-Kang Chen, Krzysztof Palczewski, Dominic Cosgrove; Light-induced translocation of RGS9-1 and Gβ5L in Mouse Rod Photoreceptors. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4078.
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© ARVO (1962-2015); The Authors (2016-present)
The transducin GTPase-accelerating protein complex, which determines the photoresponse duration of photoreceptors, is composed of RGS9-1, Gβ5L and R9AP. Here we report that RGS9-1 and Gβ5L change their distribution in rods during light/dark adaptation.
Immunohistochemistry, serial tangential section immunoblotting, immunoprecipitation and immunoblotting using anti-Phospho-RGS9 antibodies were used to study the light-induced protein translocation.
Upon prolonged dark adaptation, RGS9-1 and Gβ5L are primarily located in rod inner segments. But very dim-light exposure quickly translocates them to the outer segments. In contrast, their anchor protein R9AP remains in the outer segment at all times. In the dark, Gβ5L’s interaction with R9AP decreases significantly and RGS9-1 is phosphorylated at S475 to a significant degree. Dim light exposure leads to quick de-phosphorylation of RGS9-1. Furthermore, after prolonged dark adaptation, RGS9-1 and transducin Gα are located in different cellular compartments.
These results suggest a previously unappreciated mechanism by which prolonged dark adaptation leads to increased light sensitivity in rods by dissociating RGS9-1 from R9AP and redistributing it to rod inner segments
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