Genetically encoded chemical probes in cells reveal the binding path of urocortin-I to CRF class B GPCR

Cell. 2013 Dec 5;155(6):1258-69. doi: 10.1016/j.cell.2013.11.008. Epub 2013 Nov 27.


Molecular determinants regulating the activation of class B G-protein-coupled receptors (GPCRs) by native peptide agonists are largely unknown. We have investigated here the interaction between the corticotropin releasing factor receptor type 1 (CRF1R) and its native 40-mer peptide ligand Urocortin-I directly in mammalian cells. By incorporating unnatural amino acid photochemical and new click-chemical probes into the intact receptor expressed in the native membrane of live cells, 44 intermolecular spatial constraints have been derived for the ligand-receptor interaction. The data were analyzed in the context of the recently resolved crystal structure of CRF1R transmembrane domain and existing extracellular domain structures, yielding a complete conformational model for the peptide-receptor complex. Structural features of the receptor-ligand complex yield molecular insights on the mechanism of receptor activation and the basis for discrimination between agonist and antagonist function.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Click Chemistry / methods
  • Cross-Linking Reagents / metabolism
  • Humans
  • Mice
  • Models, Molecular*
  • Molecular Sequence Data
  • Rats
  • Receptors, Corticotropin-Releasing Hormone / chemistry*
  • Receptors, Corticotropin-Releasing Hormone / genetics
  • Receptors, Corticotropin-Releasing Hormone / metabolism*
  • Sequence Alignment
  • Urocortins / chemistry*
  • Urocortins / metabolism*


  • Cross-Linking Reagents
  • Receptors, Corticotropin-Releasing Hormone
  • UCN protein, human
  • Urocortins
  • CRF receptor type 1