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Updated: Apr 30, 2026

Measuring G-protein-coupled Receptor Signaling via Radio-labeled GTP Binding
Published on: June 9, 2017
Alpha-bulges in G protein-coupled receptors
Rob van der Kant1, Gert Vriend2
1Centre for Molecular and Biomolecular Informatics, Radboud University Medical Centre, Geert Grooteplein 26-28, 6525 GA Nijmegen, The Netherlands. Rob.vanderKant@switch.vib-kuleuven.be.
Alpha-bulges in G protein-coupled receptors (GPCRs) are crucial for ligand binding and activation. These structural elements facilitate G protein binding by enabling key helix movements during receptor activation.
Area of Science:
- Structural Biology
- Biochemistry
- Pharmacology
Background:
- G protein-coupled receptors (GPCRs) undergo conformational changes upon agonist binding, leading to G protein interaction.
- GPCR transmembrane helices are irregular, featuring kinks and alpha-bulges, with proline's role in kinks well-documented.
- The specific function of alpha-bulges in GPCR activation and ligand/G protein binding remains less explored.
Purpose of the Study:
- To highlight the significant role of alpha-bulges in GPCR transmembrane helices.
- To elucidate the involvement of alpha-bulges in ligand and G protein binding.
- To explore the contribution of alpha-bulges to GPCR activation-associated mobility.
Main Methods:
- Analysis of existing literature on GPCR structure and dynamics.
- Focus on the structural and functional implications of alpha-bulges.
- Review of molecular motions associated with GPCR activation.
Main Results:
- Alpha-bulges play a critical role in facilitating G protein binding by enabling specific helix movements.
- These movements include helix III regularization and translation, helix VI rotation, and inward helix motion.
- Alpha-bulges can appear or disappear during the GPCR activation process, suggesting their dynamic involvement.
Conclusions:
- Alpha-bulges are key structural motifs in GPCRs that directly influence ligand binding and receptor activation.
- The dynamic nature of alpha-bulges contributes significantly to the conformational changes required for G protein coupling.
- Understanding alpha-bulge function offers new insights into GPCR pharmacology and drug design.
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