Structure of the human smoothened receptor bound to an antitumour agent

Nature. 2013 May 16;497(7449):338-43. doi: 10.1038/nature12167. Epub 2013 May 1.


The smoothened (SMO) receptor, a key signal transducer in the hedgehog signalling pathway, is responsible for the maintenance of normal embryonic development and is implicated in carcinogenesis. It is classified as a class frizzled (class F) G-protein-coupled receptor (GPCR), although the canonical hedgehog signalling pathway involves the GLI transcription factors and the sequence similarity with class A GPCRs is less than 10%. Here we report the crystal structure of the transmembrane domain of the human SMO receptor bound to the small-molecule antagonist LY2940680 at 2.5 Å resolution. Although the SMO receptor shares the seven-transmembrane helical fold, most of the conserved motifs for class A GPCRs are absent, and the structure reveals an unusually complex arrangement of long extracellular loops stabilized by four disulphide bonds. The ligand binds at the extracellular end of the seven-transmembrane-helix bundle and forms extensive contacts with the loops.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Antineoplastic Agents / chemistry*
  • Antineoplastic Agents / metabolism
  • Binding Sites
  • Crystallography, X-Ray
  • Disulfides / chemistry
  • Frizzled Receptors / chemistry
  • Frizzled Receptors / classification
  • Humans
  • Ligands
  • Models, Molecular
  • Molecular Sequence Data
  • Phthalazines / chemistry*
  • Phthalazines / metabolism
  • Protein Structure, Tertiary
  • Receptors, G-Protein-Coupled / chemistry*
  • Receptors, G-Protein-Coupled / classification
  • Receptors, G-Protein-Coupled / metabolism
  • Smoothened Receptor
  • Structural Homology, Protein


  • Antineoplastic Agents
  • Disulfides
  • Frizzled Receptors
  • LY2940680
  • Ligands
  • Phthalazines
  • Receptors, G-Protein-Coupled
  • SMO protein, human
  • Smoothened Receptor

Associated data

  • PDB/4JKV