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Updated: Apr 19, 2026

Measuring G-protein-coupled Receptor Signaling via Radio-labeled GTP Binding
Published on: June 9, 2017
Single molecule analysis of functionally asymmetric G protein-coupled receptor (GPCR) oligomers reveals diverse
Kim C Jonas1, Francesca Fanelli2, Ilpo T Huhtaniemi3
1From the Institute of Reproductive and Developmental Biology, Department of Surgery and Cancer, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom.
Abstract:
Formation of G protein-coupled receptors (GPCRs) into dimers and higher order oligomers represents a key mechanism in pleiotropic signaling, yet how individual protomers function within oligomers remains poorly understood. We present a super-resolution imaging approach, resolving single GPCR molecules to ∼ 8 nm resolution in functional asymmetric dimers and oligomers using dual-color photoactivatable dyes and localization microscopy (PD-PALM). PD-PALM of two functionally defined mutant luteinizing hormone receptors (LHRs), a ligand-binding deficient receptor (LHR(B-)) and a signaling-deficient (LHR(S-)) receptor, which only function via intermolecular cooperation, favored oligomeric over dimeric formation. PD-PALM imaging of trimers and tetramers revealed specific spatial organizations of individual protomers in complexes where the ratiometric composition of LHR(B-) to LHR(S-) modulated ligand-induced signal sensitivity. Structural modeling of asymmetric LHR oligomers strongly aligned with PD-PALM-imaged spatial arrangements, identifying multiple possible helix interfaces mediating inter-protomer associations. Our findings reveal that diverse spatial and structural assemblies mediating GPCR oligomerization may acutely fine-tune the cellular signaling profile.
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