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Imaging G-protein Coupled Receptor (GPCR)-mediated Signaling Events that Control Chemotaxis of Dictyostelium Discoideum
Published on: September 20, 2011
A self-scaffolding model for G protein signaling
Jingting Wang1, Urszula Golebiewska, Suzanne Scarlata
1Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794-8661, USA.
Journal of Molecular Biology
|April 14, 2009
Summary
G protein activation may not require subunit dissociation. Studies show G protein subunits can remain complexed while activating effectors, suggesting stable signaling complexes.
Area of Science:
- Cellular signaling
- Molecular biology
- Biochemistry
Background:
- Heterotrimeric G proteins are key signal transducers.
- Activation typically involves Galpha and Gbetagamma subunit dissociation.
- Previous work suggested Galphaq remains complexed with phospholipase Cbeta1.
Purpose of the Study:
- To investigate if G protein subunits remain associated after activation in other systems.
- To determine if stable signaling complexes form between G proteins and effectors.
- To elucidate the structural basis for G protein-effector complex stabilization.
Main Methods:
- Förster resonance energy transfer (FRET) studies in HEK293 cells.
- In vitro studies using fluorescence-tagged single-Cys mutants.
- Monitoring protein interactions, fluorescence properties, and accessibility upon activation.
Main Results:
- eYFP-Galphai and eCFP-Gbetagamma remained associated after stimulation.
- Significant, unchanged FRET between Alexa546-phospholipase Cbeta2 and eGFP-Gbetagamma upon activation.
- In vitro studies indicated a change in orientation between G protein subunits upon activation.
Conclusions:
- G protein subunits can remain complexed during activation and effector interaction.
- Stable signaling complexes can form between G proteins and their effectors.
- A conformational change in G protein orientation may facilitate sustained effector activation while maintaining subunit association.
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