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Mapping the Binding of G Protein–Coupled Receptor Kinases 4γ (GRK4γ) with Gα s
Author(s) -
Nguyen Jenny H,
Lacuran Alecander E,
Oelschlaeger Peter,
Andresen Bradley T
Publication year - 2013
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.27.1_supplement.1172.1
Subject(s) - g protein coupled receptor kinase , receptor , chemistry , ww domain , adenylyl cyclase , g protein coupled receptor , biology , biophysics , microbiology and biotechnology , biochemistry , gene
GRK4γ appears to be constitutively active and two polymorphisms in the RH domain (R65L and A142V) and one in the kinase domain (KD) (A486V) are associated with hypertension. Currently our model is that GRK4γ interacts with inactive Gα s through part of the Gα s helical domain. Since GRK2's RH domain interacts with Gα q , we hypothesized that GRK4γ interacts with inactive Gα s through its RH domain. Since GRK4γ, but not GRK5, interacts with inactive Gα s , we utilized a chimeric approach and co‐immunoprecipitation to identify the region that GRK4γ binds to Gα s . Initially we constructed chimeras of GRK4 & 5 examining multiple helices in the RH domain as well as the point where the RH domain polymorphisms lie. In contrast with the hypothesis, our data indicate that GRK4γ interacts with either the KD or distal portion of the RH domain which is largely absent in GRK4γ. GRK4γ was modeled from GRK6 (PBD:3NYO), and Autodock 4.2 was used to predict other potential Gα s ‐helical domain binding sites on GRK4γ. Further chimeric based analysis indicates that the likely mode of interaction is through a region at the distal end of GRK4γ, which is distinct from GRK5. Our current model indicates that GRK4γ is poised next to the receptor allowing for it to efficiently phosphorylate the receptor after Gα s dissociates and binds to adenylyl cyclase, but fails to explain the mechanistic consequence of the R65L and A142V polymorphisms.