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Updated: Jun 6, 2026

Transmembrane Domain Oligomerization Propensity determined by ToxR Assay
Published on: May 26, 2011
Trans-activation between 7TM domains: implication in heterodimeric GABAB receptor activation
Carine Monnier1, Haijun Tu, Emmanuel Bourrier
1CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Département de Pharmacologie Moléculaire, Montpellier, France.
This study demonstrates direct trans-activation between seven-transmembrane (7TM) proteins using the GABAB receptor. This finding validates how interacting 7TM receptors communicate functionally.
Area of Science:
- Molecular and Cellular Biology
- Neuroscience
- Pharmacology
Background:
- Seven-transmembrane (7TM) receptors are crucial for cell communication.
- These receptors can form dimers or oligomers, potentially enabling functional cross-talk.
- The hypothesis of trans-activation between interacting 7TM receptors requires experimental validation.
Purpose of the Study:
- To investigate direct allosteric coupling between 7TM domains in GABAB receptor heterodimers.
- To validate the hypothesis of functional trans-activation between interacting 7TM proteins.
Main Methods:
- Utilized a novel orthogonal-labeling approach based on ACP- and SNAP-tag technologies.
- Employed time-resolved Förster Resonance Energy Transfer (TR-FRET) to verify heterodimerization.
- Studied wild-type and mutated GABAB subunits, including a construct with a deleted GABAB2 extracellular domain.
Main Results:
- Demonstrated direct allosteric coupling between the 7TM domains of GABAB heterodimers.
- Showed that a GABAB receptor lacking the GABAB2 extracellular domain could still activate G proteins.
- Confirmed that ligands targeting the GABAB2 7TM enhanced agonist affinity at the GABAB1 subunit in the mutated receptor.
Conclusions:
- Provided new insights into GABAB receptor activation mechanisms.
- Provided clear evidence for direct trans-activation between the 7TM domains of two interacting proteins.
- Established a model system for studying functional cross-talk in 7TM receptor complexes.
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