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Coupled Motions in β2AR:Gαs Conformational Ensembles
Dimitar V Pachov1,2, Rasmus Fonseca2,3, Damien Arnol4,5
1Department of Chemistry, Stanford University , Stanford, California 94305, United States.
Journal of Chemical Theory and Computation
|January 13, 2016
Summary
This study reveals how G protein-coupled receptors (GPCRs) and G proteins form complexes and activate. Precoupling allosterically modulates receptors, leading to collective activation upon agonist binding, impacting GPCR drug discovery.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- G protein-coupled receptors (GPCRs) mediate cellular responses via signal transduction.
- Understanding GPCR-G protein complex formation and G protein activation remains a challenge.
Purpose of the Study:
- To elucidate the mechanism of GPCR-G protein complex formation and activation.
- To investigate the role of precoupling in modulating receptor activity.
Main Methods:
- In silico conformational ensemble analysis of inactive β2AR:Gαs complexes.
- Examination of conformational coupling between receptor and G protein structural elements.
Main Results:
- Inactive GPCR-G protein complexes sample intermediate states, showing conformational coupling.
- Identified novel interactions involving Gαs helix αN and intracellular loop 2 in G protein activation.
- Observed modulation of these interactions in the active state.
Conclusions:
- Proposes an alternative model of G protein activation involving precoupling and allosteric modulation.
- Agonist binding induces collective activation of the pre-coupled complex.
- Findings have broad implications for GPCR drug discovery and understanding signaling pathways.
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