Title : Structural mechanism of ligand activation in human GABA(B)
receptor
Abstract :
- Human GABA(B) (γ-aminobutyric acid class B) receptor is a G-protein-coupled receptor central to inhibitory neurotransmission in the brain
- It functions as an obligatory heterodimer of the subunits GBR1 and GBR2
- Here we present the crystal structures of a heterodimeric complex between the extracellular domains of GBR1 and GBR2 in the apo , agonist-bound and antagonist-bound forms
- The apo and antagonist-bound structures represent the resting state of the receptor ; the agonist-bound complex corresponds to the active state
- Both subunits adopt an open conformation at rest, and only GBR1 closes on agonist-induced receptor activation
- The agonists and antagonists are anchored in the interdomain crevice of GBR1 by an overlapping set of residues
- An antagonist confines GBR1 to the open conformation of the inactive state, whereas an agonist induces its domain closure for activation
- Our data reveal a unique activation mechanism for GABA(B) receptor that involves the formation of a novel heterodimer interface between subunits
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