Molecular Basis for Hormone Recognition and Activation of Corticotropin-Releasing Factor Receptors.
Ma, S., Shen, Q., Zhao, L.H., Mao, C., Zhou, X.E., Shen, D.D., de Waal, P.W., Bi, P., Li, C., Jiang, Y., Wang, M.W., Sexton, P.M., Wootten, D., Melcher, K., Zhang, Y., Xu, H.E.(2020) Mol Cell 77: 669
- PubMed: 32004470 
- DOI: https://doi.org/10.1016/j.molcel.2020.01.013
- Primary Citation of Related Structures:  
6PB0, 6PB1 - PubMed Abstract: 
Corticotropin-releasing factor (CRF) and the three related peptides urocortins 1-3 (UCN1-UCN3) are endocrine hormones that control the stress responses by activating CRF1R and CRF2R, two members of class B G-protein-coupled receptors (GPCRs). Here, we present two cryoelectron microscopy (cryo-EM) structures of UCN1-bound CRF1R and CRF2R with the stimulatory G protein. In both structures, UCN1 adopts a single straight helix with its N terminus dipped into the receptor transmembrane bundle. Although the peptide-binding residues in CRF1R and CRF2R are different from other members of class B GPCRs, the residues involved in receptor activation and G protein coupling are conserved. In addition, both structures reveal bound cholesterol molecules to the receptor transmembrane helices. Our structures define the basis of ligand-binding specificity in the CRF receptor-hormone system, establish a common mechanism of class B GPCR activation and G protein coupling, and provide a paradigm for studying membrane protein-lipid interactions for class B GPCRs.
Organizational Affiliation: 
The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; University of Chinese Academy of Sciences, Beijing 100049, China.