Abstract
We used fluorescence resonance energy transfer imaging of enhanced cyan fluorescent protein (CFP)-tagged and enhanced yellow fluorescent protein (YFP)-tagged protein pairs to examine the hypothesis that G protein γ subunit-like (GGL) domain-containing regulators of G protein signaling (RGS) can directly bind to the Gβ5 subunit of heterotrimeric G proteins in vivo. We observed that Gβ5 could interact with Gγ2 and Gγ13, after their expression in human embryonic kidney 293 cells. Interestingly, although untagged Gγ3 did not interact with Gβ5, CFP-tagged Gγ3 strongly interacted with YFP-tagged Gβ5 in FRET studies. Moreover, CFP-Gγ3 supported Ca2+ channel inhibition when paired with Gβ5 or YFP-Gβ5, indicating a “gain of function” for CFP-Gγ3. Gβ5 could also interact with RGS11 and its N-terminal, but not its C-terminal domain. On the other hand, RGS11 did not interact with Gβ1. These studies demonstrate that the GGL domain-containing N terminus of RGS 11 can directly interact with Gβ5 in vivo and supports the hypothesis that this interaction may contribute to the specificity of Gβ5 interactions with cellular effector molecules.
Footnotes
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This study was supported by U.S. Public Health Service Grant MH-40165. Preliminary results were presented in abstract format at the 2001 Neuroscience Meeting (Abstract 271.7).
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DOI: 10.1124/jpet.102.048637
- Abbreviations:
- GPCR
- G protein-coupled receptor
- VDCC
- voltage-dependent Ca2+ channel
- RGS
- regulator of G protein signaling
- GGL
- G protein γ subunit-like
- GTPase-activating protein
- FRET, fluorescence resonance energy transfer
- YFP
- yellow fluorescent protein
- CFP
- cyan fluorescent protein
- ANOVA
- analysis of variance
- FRETN
- normalized fluorescence resonance energy transfer
- ROI
- region of interest
- aa
- amino acid
- Received January 1, 2003.
- Accepted February 6, 2003.
- The American Society for Pharmacology and Experimental Therapeutics
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