Single Molecule Analysis of Functionally Asymmetric G Protein-coupled Receptor (GPCR) Oligomers Reveals Diverse Spatial and Structural Assemblies




Jonas KC, Fanelli F, Huhtaniemi IT, Hanyaloglu AC

PublisherAMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

2015

 Journal of Biological Chemistry

JOURNAL OF BIOLOGICAL CHEMISTRY

J BIOL CHEM

290

7

3875

3892

18

0021-9258

1083-351X

DOIhttps://doi.org/10.1074/jbc.M114.622498



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 similar 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 (LHRB-) and a signaling-deficient (LHRS-) 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 LHRB- to LHRS- 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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