Structural insight into apelin receptor-G protein stoichiometry

  • Nat Struct Mol Biol. 2022 Jul;29(7):688-697. doi: 10.1038/s41594-022-00797-5.
Yang Yue  #  1 ,  Lier Liu  #  1  2  3 ,  Li-Jie Wu  #  1 ,  Yiran Wu  1 ,  Ling Wang  1 ,  Fei Li  1 ,  Junlin Liu  1 ,  Gye-Won Han  4 ,  Bo Chen  1 ,  Xi Lin  1 ,  Rebecca L Brouillette  5 ,  Émile Breault  5 ,  Jean-Michel Longpré  5 ,  Songting Shi  6 ,  Hui Lei  6 ,  Philippe Sarret  5 ,  Raymond C Stevens  1  2  6 ,  Michael A Hanson  6 ,  Fei Xu  7  8  9
Affiliations
  • 1. iHuman Institute, ShanghaiTech University, Shanghai, China.
  • 2. School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
  • 3. University of Chinese Academy of Sciences, Beijing, China.
  • 4. Departments of Biological Sciences and Chemistry, Bridge Institute, University of Southern California, Los Angeles, CA, USA.
  • 5. Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Institute of Pharmacology at Sherbrooke, University of Sherbrooke, Sherbrooke, Quebec, Canada.
  • 6. Structure Therapeutics, South San Francisco, CA, USA.
  • 7. iHuman Institute, ShanghaiTech University, Shanghai, China. [email protected].
  • 8. School of Life Science and Technology, ShanghaiTech University, Shanghai, China. [email protected].
  • 9. University of Chinese Academy of Sciences, Beijing, China. [email protected].
  • # Contributed equally.
PMID: 35817871 DOI: 10.1038/s41594-022-00797-5
Abstract

The technique of cryogenic-electron microscopy (cryo-EM) has revolutionized the field of membrane protein structure and function with a focus on the dominantly observed molecular species. This report describes the structural characterization of a fully active human apelin receptor (APJR) complexed with heterotrimeric G protein observed in both 2:1 and 1:1 stoichiometric ratios. We use cryo-EM single-particle analysis to determine the structural details of both species from the same sample preparation. Protein preparations, in the presence of the endogenous peptide ligand ELA or a synthetic small molecule, both demonstrate these mixed stoichiometric states. Structural differences in G protein engagement between dimeric and monomeric APJR suggest a role for the stoichiometry of G protein-coupled receptor- (GPCR-)G protein coupling on downstream signaling and receptor pharmacology. Furthermore, a small, hydrophobic dimer interface provides a starting framework for additional class A GPCR dimerization studies. Together, these findings uncover a mechanism of versatile regulation through oligomerization by which GPCRs can modulate their signaling.