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-Structure paper
Title | GPR161 structure uncovers the redundant role of sterol-regulated ciliary cAMP signaling in the Hedgehog pathway. |
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Journal, issue, pages | bioRxiv, Year 2023 |
Publish date | May 24, 2023 |
Authors | Nicholas Hoppe / Simone Harrison / Sun-Hee Hwang / Ziwei Chen / Masha Karelina / Ishan Deshpande / Carl-Mikael Suomivuori / Vivek R Palicharla / Samuel P Berry / Philipp Tschaikner / Dominik Regele / Douglas F Covey / Eduard Stefan / Debora S Marks / Jeremy Reiter / Ron O Dror / Alex S Evers / Saikat Mukhopadhyay / Aashish Manglik / |
PubMed Abstract | The orphan G protein-coupled receptor (GPCR) GPR161 is enriched in primary cilia, where it plays a central role in suppressing Hedgehog signaling. GPR161 mutations lead to developmental defects and ...The orphan G protein-coupled receptor (GPCR) GPR161 is enriched in primary cilia, where it plays a central role in suppressing Hedgehog signaling. GPR161 mutations lead to developmental defects and cancers. The fundamental basis of how GPR161 is activated, including potential endogenous activators and pathway-relevant signal transducers, remains unclear. To elucidate GPR161 function, we determined a cryogenic-electron microscopy structure of active GPR161 bound to the heterotrimeric G protein complex G. This structure revealed an extracellular loop 2 that occupies the canonical GPCR orthosteric ligand pocket. Furthermore, we identify a sterol that binds to a conserved extrahelical site adjacent to transmembrane helices 6 and 7 and stabilizes a GPR161 conformation required for G coupling. Mutations that prevent sterol binding to GPR161 suppress cAMP pathway activation. Surprisingly, these mutants retain the ability to suppress GLI2 transcription factor accumulation in cilia, a key function of ciliary GPR161 in Hedgehog pathway suppression. By contrast, a protein kinase A-binding site in the GPR161 C-terminus is critical in suppressing GLI2 ciliary accumulation. Our work highlights how unique structural features of GPR161 interface with the Hedgehog pathway and sets a foundation to understand the broader role of GPR161 function in other signaling pathways. |
External links | bioRxiv / PubMed:37292845 / PubMed Central |
Methods | EM (single particle) |
Resolution | 2.74 Å |
Structure data | EMDB-40603, PDB-8smv: |
Chemicals | ChemComp-CLR: |
Source |
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Keywords | MEMBRANE PROTEIN / GPCR / orphan / active / Hedgehog |