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Publication Abstract from PubMed

G protein-coupled receptors (GPCRs) mediate transmembrane signaling. Before ligand binding, GPCRs exist in a basal state. Crystal structures of several GPCRs bound with antagonists or agonists have been solved. However, the crystal structure of the ligand-free basal state of a GPCR, the starting point of GPCR activation and function, had not yet been determined. Here we report the X-ray crystal structure of the ligand-free basal state of a GPCR in a lipid membrane-like environment. Oligomeric turkey beta1-adrenergic receptors display two dimer interfaces. One interface involves the transmembrane domain (TM) 1, TM2, the C-terminal H8 and extracellular loop 1. The other interface engages residues from TM4, TM5, intracellular loop 2 and extracellular loop 2. Structural comparisons show that this ligand-free state is in an inactive conformation. This provides the structural basis of GPCR dimerization and oligomerization.

Crystal structure of oligomeric beta1-adrenergic G protein-coupled receptors in ligand-free basal state.,Huang J, Chen S, Zhang JJ, Huang XY Nat Struct Mol Biol. 2013 Apr;20(4):419-25. doi: 10.1038/nsmb.2504. Epub 2013 Feb, 24. PMID:23435379^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.