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Single Molecule Analysis of Functionally Asymmetric G Protein-coupled Receptor (GPCR) Oligomers Reveals Diverse Spatial and Structural Assemblies
Tekijät: Jonas KC, Fanelli F, Huhtaniemi IT, Hanyaloglu AC
Kustantaja: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Julkaisuvuosi: 2015
Journal: Journal of Biological Chemistry
Tietokannassa oleva lehden nimi: JOURNAL OF BIOLOGICAL CHEMISTRY
Lehden akronyymi: J BIOL CHEM
Vuosikerta: 290
Numero: 7
Aloitussivu: 3875
Lopetussivu: 3892
Sivujen määrä: 18
ISSN: 0021-9258
eISSN: 1083-351X
DOI: https://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.