Abstract
Purpose: :
G proteins are known to be major players in visual signal transduction. In the retina, G protein signaling is critically shaped by the R7 group of Regulator of G Protein Signaling (R7 RGS) family. Currently, molecular context of R7 RGS protein function is understood only for RGS9, a key regulator of photoreceptor signaling. Other R7 RGS proteins are abundant in the inner retina where they are thought to regulate G protein signal transduction cascades downstream from the photoreceptors. In the efforts to understand the molecular composition of such pathways we conducted a search for the interaction partners of an R7 RGS member, RGS6.
Methods: :
Immunoprecipitation with anti RGS6 antibodies was used for isolation of RGS6-containing complexes. Eluates were resolved by gel electrophoresis. Coomasie-stained bands were excised, digested with trypsin and subjected to mass-spectrometric identification by MALDI TOF spectrometry. Data was analyzed using ProteinPilot software.
Results: :
Analysis of proteins eluted from antibodies indicated a presence of several unique bands which were not found in the control immunoprecipitation experiment with retinas lacking RGS6. Retinal RGS6 was present as a single major species of approximately 54kDa. The most prominent co-precipitating protein was identified as short splice isoform of Gbeta5. Additionally, several novel interactions were found.
Conclusions: :
RGS6 in the retina exists as a macromolecular complex involving short splice isoform of Gbeta5.
Keywords: retina • proteomics • signal transduction