RGS3 interacts with 14-3-3 via the N-terminal region distinct from the RGS (regulator of G-protein signalling) domain.
RGS3 belongs to a family of the regulators of G-protein signalling (RGS), which bind and inhibit the G alpha subunits of heterotrimeric G-proteins via a homologous RGS domain. Increasing evidence suggests that RGS proteins can also interact with targets other than G-proteins. Employing yeast two-hybrid screening of a cDNA library, we identified an interaction between RGS3 and the phosphoserine-binding protein 14-3-3. This interaction was confirmed by in vitro binding and co-immunoprecipitation experiments. RGS3-deletion analysis revealed the presence of a single 14-3-3-binding site located outside of the RGS domain. Ser(264) was then identified as the 14-3-3-binding site of RGS3. The S(264)A mutation resulted in the loss of RGS3 binding to 14-3-3, without affecting its ability to bind G alpha(q). Signalling studies showed that the S(264)A mutant was more potent than the wild-type RGS3 in inhibition of G-protein-mediated signalling. Binding experiments revealed that RGS3 exists in two separate pools, either 14-3-3-bound or G-protein-bound, and that the 14-3-3-bound RGS3 is unable to interact with G-proteins. These data are consistent with the model wherein 14-3-3 serves as a scavenger of RGS3, regulating the amounts of RGS3 available for binding G-proteins. This study describes a new level in the regulation of G-protein signalling, in which the inhibitors of G-proteins, RGS proteins, can themselves be regulated by phosphorylation and binding 14-3-3.
Niu
Jiaxin
J
Department of Pharmacology, University of Illinois at Chicago College of Medicine, Chicago, IL 60612, U.S.A.
Scheschonka
Astrid
A
Druey
Kirk M
KM
Davis
Amanda
A
Reed
Eleanor
E
Kolenko
Vladimir
V
Bodnar
Richard
R
Voyno-Yasenetskaya
Tatyana
T
Du
Xiaoping
X
Kehrl
John
J
Dulin
Nickolai O
NO
D048948:14-3-3 Proteins; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D006224:Cricetinae; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D015723:Gene Library; D017930:Genes, Reporter; D006801:Humans; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D020710:RGS Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D014446:Tyrosine 3-Monooxygenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050807:ets-Domain Protein Elk-1
D048948:14-3-3 Proteins; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D020690:GTPase-Activating Proteins; D011518:Proto-Oncogene Proteins; D020710:RGS Proteins; C485898:RGS3 protein, human; D011993:Recombinant Fusion Proteins; C415085:Rgs3 protein, mouse; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; D014446:Tyrosine 3-Monooxygenase; D019204:GTP-Binding Proteins