Biased Signaling Pathways in β2-Adrenergic Receptor Characterized by 19F-NMR

JJ Liu, R Horst, V Katritch, RC Stevens, K Wüthrich - Science, 2012 - science.org
Science, 2012science.org
Extracellular ligand binding to G protein–coupled receptors (GPCRs) modulates G protein
and β-arrestin signaling by changing the conformational states of the cytoplasmic region of
the receptor. Using site-specific 19F-NMR (fluorine-19 nuclear magnetic resonance) labels
in the β2-adrenergic receptor (β2AR) in complexes with various ligands, we observed that
the cytoplasmic ends of helices VI and VII adopt two major conformational states. Changes
in the NMR signals reveal that agonist binding primarily shifts the equilibrium toward the G …
Extracellular ligand binding to G protein–coupled receptors (GPCRs) modulates G protein and β-arrestin signaling by changing the conformational states of the cytoplasmic region of the receptor. Using site-specific 19F-NMR (fluorine-19 nuclear magnetic resonance) labels in the β2-adrenergic receptor (β2AR) in complexes with various ligands, we observed that the cytoplasmic ends of helices VI and VII adopt two major conformational states. Changes in the NMR signals reveal that agonist binding primarily shifts the equilibrium toward the G protein–specific active state of helix VI. In contrast, β-arrestin–biased ligands predominantly impact the conformational states of helix VII. The selective effects of different ligands on the conformational equilibria involving helices VI and VII provide insights into the long-range structural plasticity of β2AR in partial and biased agonist signaling.
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