G protein-coupled receptors and resistance to inhibitors of cholinesterase-8A (Ric-8A) both regulate the regulator of g protein signaling 14 RGS14·G?i1 complex in live cells.

ABSTRACT: Regulator of G protein Signaling 14 (RGS14) is a multifunctional scaffolding protein that integrates both conventional and unconventional G protein signaling pathways. Like other RGS (regulator of G protein signaling) proteins, RGS14 acts as a GTPase accelerating protein to terminate conventional G?(i/o) signaling. However, unlike other RGS proteins, RGS14 also contains a G protein regulatory/GoLoco motif that specifically binds G?(i1/3)-GDP in cells and in vitro. The non-receptor guanine nucleotide exchange factor Ric-8A can bind and act on the RGS14·G?(i1)-GDP complex to play a role in unconventional G protein signaling independent of G protein-coupled receptors (GPCRs). Here we demonstrate that RGS14 forms a G?(i/o)-dependent complex with a G(i)-linked GPCR and that this complex is regulated by receptor agonist and Ric-8A (resistance to inhibitors of cholinesterase-8A). Using live cell bioluminescence resonance energy transfer, we show that RGS14 functionally associates with the ?(2A)-adrenergic receptor (?(2A)-AR) in a G?(i/o)-dependent manner. This interaction is markedly disrupted after receptor stimulation by the specific agonist UK14304, suggesting complex dissociation or rearrangement. Agonist-mediated dissociation of the RGS14·?(2A)-AR complex occurs in the presence of G?(i/o) but not G?(s) or G?(q). Unexpectedly, RGS14 does not dissociate from G?(i1) in the presence of stimulated ?(2A)-AR, suggesting preservation of RGS14·G?(i1) complexes after receptor activation. However, Ric-8A facilitates dissociation of both the RGS14·G?(i1) complex and the G?(i1)-dependent RGS14·?(2A)-AR complex after receptor activation. Together, these findings indicate that RGS14 can form complexes with GPCRs in cells that are dependent on G?(i/o) and that these RGS14·G?(i1)·GPCR complexes may be substrates for other signaling partners such as Ric-8A.

SUBMITTER: Vellano CP 

PROVIDER: S-EPMC3207400 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature