Cholesterol Interaction Sites on the Transmembrane Domain of the Hedgehog Signal Transducer and Class F G Protein-Coupled Receptor Smoothened

Structure. 2019 Mar 5;27(3):549-559.e2. doi: 10.1016/j.str.2018.11.003. Epub 2018 Dec 27.


Transduction of Hedgehog signals across the plasma membrane is facilitated by the class F G-protein-coupled-receptor (GPCR) Smoothened (SMO). Recent studies suggest that SMO is modulated via interactions of its transmembrane (TM) domain with cholesterol. We apply molecular dynamics simulations of SMO embedded in cholesterol containing lipid bilayers, revealing a direct interaction of cholesterol with the TM domain at regions distinct from those observed in class A GPCRs. In particular the extracellular tips of helices TM2 and TM3 form a well-defined cholesterol interaction site. Potential of mean force calculations yield a free energy landscape for cholesterol binding. Alongside analysis of equilibrium cholesterol occupancy, this reveals the existence of a dynamic "greasy patch" interaction with the TM domain of SMO, which may be compared with previously identified lipid interaction sites on other membrane proteins. These predictions provide molecular-level insights into cholesterol interactions with a class F GPCR, suggesting potential druggable sites.

Keywords: Frizzled; GPCR; Hedgehog; Smoothened; cell signaling; cholesterol; lipid; membrane; molecular dynamics; multiscale simulation.

Publication types

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

MeSH terms

  • Binding Sites
  • Cholesterol / metabolism*
  • Humans
  • Lipid Bilayers / metabolism
  • Models, Molecular
  • Molecular Dynamics Simulation
  • Phosphatidylinositol 4,5-Diphosphate / metabolism
  • Protein Binding
  • Protein Domains
  • Protein Structure, Secondary
  • Smoothened Receptor / chemistry*
  • Smoothened Receptor / metabolism*


  • Lipid Bilayers
  • Phosphatidylinositol 4,5-Diphosphate
  • SMO protein, human
  • Smoothened Receptor
  • Cholesterol