A structural basis for amylin receptor phenotype

Abstract

Amylin receptors (AMYRs) are heterodimers of the calcitonin (CT) receptor (CTR) and one of three receptor activity–modifying proteins (RAMPs), AMY 1 R, AMY 2 R, and AMY 3 R. Selective AMYR agonists and dual AMYR/CTR agonists are being developed as obesity treatments; however, the molecular basis for peptide binding and selectivity is unknown. We determined the structure and dynamics of active AMYRs with amylin, AMY 1 R with salmon CT (sCT), AMY 2 R with sCT or human CT (hCT), and CTR with amylin, sCT, or hCT. The conformation of amylin-bound complexes was similar for all AMYRs, constrained by the RAMP, and an ordered midpeptide motif that we call the bypass motif. The CT-bound AMYR complexes were distinct, overlapping the CT-bound CTR complexes. Our findings indicate that activation of AMYRs by CT-based peptides is distinct from their activation by amylin-based peptides. This has important implications for the development of AMYR therapeutics.

Hydrogen-bond networks for proton couplings in G-Protein coupled receptors

“…Cryo-EM structures solved were recently at resolutions of 2.0-3.3 Å for ligand-bound G s -CTR and Gs-AMY 1-3 R [72]. Protein-water H-bonds were suggested to help stabilize the active conformation of the receptor, and to contribute to the binding of sCT [72].…”

“…Cryo-EM structures solved were recently at resolutions of 2.0-3.3 Å for ligand-bound G s -CTR and Gs-AMY 1-3 R [72]. Protein-water H-bonds were suggested to help stabilize the active conformation of the receptor, and to contribute to the binding of sCT [72]. The H-bond graph we computed for the CTR domain contains 51 sidechain-sidechain and watermediated H-bonds; the largest H-bond clusters contain two water molecules each and 5-6 protein sidechains (Figure 2J).…”

Molecular insights into peptide agonist engagement with the PTH1 receptor

“…Notably, a water makes bridging hydrogen bonds to the backbones of G418 6.50 and I371 5.47 ( Figure 3c; Table S1 ). Equivalent waters were observed in the case of the GLP-1R, as well as in the more distantly related calcitonin receptor (Cao et al ., 2022), illustrating importance of waters in activation mechanisms, and stabilisation of the G protein coupled state that is conserved across class B1 GPCRs.…”

Targeting VIP and PACAP Receptor Signaling: New Insights into Designing Drugs for the PACAP Subfamily of Receptors

“…Structures of PAC1, VPAC1, and VPAC2 receptors determined by cryo-EM are consistent with the proposed class B1 GPCR two-domain activation model, where the C-terminal portion of the peptide agonist binds to the peptide-binding cleft within the ECD [ 135 , 299 ], while the N-terminal helix of the peptide interacts with the receptor core. The N-terminal ECD of the receptor forms a horseshoe-like configuration around the peptide, extending towards the receptor core to form interactions with the top of ECL1 [ 135 , 136 , 137 , 300 , 301 , 302 , 303 , 304 , 305 , 306 , 307 , 308 , 309 ].…”

“… Comparisons of the binding mode of representative peptides bound to Class B1 GPCRs reveal a shared peptide binding mode where the N-terminus of the peptide interacts with the transmembrane (TM) core and the C-terminus of the peptide interacts with the N-terminal extracellular domain (ECD) and extracellular loops (ECLs) of the receptor [ 135 , 136 , 137 , 300 , 301 , 302 , 303 , 304 , 305 , 306 , 307 , 308 , 309 ]. The highest variability of the structures is in the extracellular domains and peptide C-termini (as displayed in the structure overlay in the first panel.…”