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Homo‐Oligomerization of Regulator Of G Protein Signaling 7 (RGS7)
Author(s) -
Slepak Vladlen Z,
Tayou Junior,
Wang Qiang,
Pronin Alexey
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1190.12
Subject(s) - g protein coupled receptor , g protein , immunoprecipitation , gtpase activating protein , microbiology and biotechnology , protein subunit , gtp binding protein regulators , chemistry , receptor , biology , signal transduction , biochemistry , gene
RGS proteins belonging to the R7 subfamily (RGS6, 7, 9 and 11) are highly expressed in the CNS neurons and to a much lesser extent in glands and heart where they regulate many physiological processes. R7 proteins contain several distinct domains and form obligatory dimers with the atypical Gβ subunit, Gβ5, which is essential for the stability of these complexes. They also interact with other proteins such as R7BP (R7‐binding protein), R9AP (R9‐anchoring protein) and the orphan G protein coupled receptors, GPR158 and GPR179. These interactions modulate the function of R7 proteins, facilitate their stability and targeting to plasma membranes. In neurons and transfected cells, RGS7 localizes not only to the plasma membrane but also to cytoplasmic granules where its function is unknown. Here, using chemical cross‐linking, immunoprecipitation and mass spectrometry approaches, we sought to identify new binding partners of granular RGS7. We found that RGS7 can exist as a homo‐oligomer that after cross‐linking has the apparent molecular weight of approximately 150 kDa upon resolution by SDS PAGE. Formation of this oligomeric complex was confirmed by co‐immunoprecipitation assays with or without cross‐linking. The RGS7‐RGS7 interaction requires the DEP domain, but not the RGS, DHEX domains or the obligatory subunit of RGS7, Gβ5. We also demonstrated that oligomerization of RGS7 was inhibited in the presence of R7BP or constitutively activated Gαo. However, GPR158 could bind to the oligomeric form of RGS7. While oligomerization of other proteins in G protein signaling (e.g., GPCRs or arresting) is known, or results for the first time show the existence of RGS protein homo‐oligomers. Support or Funding Information This work is supported by NIH Grant R01DK105427 (VZS)