Fig. 4: Unique conformation of the N-terminal α-helix of VIP2R in class B1 GPCRs.
From: A distinctive ligand recognition mechanism by the human vasoactive intestinal polypeptide receptor 2
a Close-up view of the PACAP27–ECD–ECL1 interface shows that the N-terminal α-helix filled the cleft between PACAP27 and ECL1, thereby stabilizing the complex. b Signaling profiles of VIP2R with truncated or extended ECD and substitution of the N-terminal α-helix or ECD from PAC1R in response to PACAP27. Data are presented as means ± S.E.M. of at least three independent experiments (n = 3–6). Source data are provided as a Source Data file. WT, wild-type. Δ, residue truncation. [AA]2, extend the receptor N terminus by two amino acids (GS); [AA]5, five amino acids (GSSGG); [AA]10, ten amino acids (GSSGGGGSGG). c Conformational comparison of the N-terminal α-helix among peptide-bound class B1 GPCR structures. All structures are superimposed on the GLP-1-bound GLP-1R (PDB code: 6X18)24 using the Cα carbons of the TMD residues. The receptor is shown in gray, peptide in green, ECL1 in pink, and the N-terminal α-helix in red.
