(A) Percentage of GPCR structures in the PDB
determined by Cryo-EM
per year. (B) Cumulative numbers of GPCR structures determined by
X-ray crystallography and Cryo-EM, which include multiple structures
of the same receptor bound to different ligands, intracellular binding
partners, or non-native species. The data for 2021 includes only the
first seven months of the year. A, B: Reprinted with permission from
ref (841) under Creative
Commons licenses. (C) Schematic of the activation of a class B GPCR
by extracellular peptide agonist via a “two-domain”
binding mechanism. (D) Cryo-EM density map of the GLP-1R:Gs complex,
colored by subunits (transmembrane domains in light green, NTD in
dark green, GLP1 peptide in orange, Gαs Ras-like
in gold, Gβ in light blue, Gγ in
dark blue, and Nb35 in gray). GLP-1R (PDB ID: 5EE7). (E) Structure
of the activated GLP-1R:Gs complex in the same view and color scheme
as shown in D. C–E: Reprinted with permission from ref (842). Copyright 2017 Springer
Nature.