Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-55831
Cell 2018 Jul 12;1742:312-324.e16. doi: 10.1016/j.cell.2018.04.029.
Show Gene links Show Anatomy links

Structural Basis of Smoothened Activation in Hedgehog Signaling.

Huang P , Zheng S , Wierbowski BM , Kim Y , Nedelcu D , Aravena L , Liu J , Kruse AC , Salic A .


???displayArticle.abstract???
The seven-transmembrane-spanning protein Smoothened is the central transducer in Hedgehog signaling, a pathway fundamental in development and in cancer. Smoothened is activated by cholesterol binding to its extracellular cysteine-rich domain (CRD). How this interaction leads to changes in the transmembrane domain and Smoothened activation is unknown. Here, we report crystal structures of sterol-activated Smoothened. The CRD undergoes a dramatic reorientation, allosterically causing the transmembrane domain to adopt a conformation similar to active G-protein-coupled receptors. We show that Smoothened contains a unique inhibitory π-cation lock, which is broken on activation and is disrupted in constitutively active oncogenic mutants. Smoothened activation opens a hydrophobic tunnel, suggesting a pathway for cholesterol movement from the inner membrane leaflet to the CRD. All Smoothened antagonists bind the transmembrane domain and block tunnel opening, but cyclopamine also binds the CRD, inducing the active transmembrane conformation. Together, these results define the mechanisms of Smoothened activation and inhibition.

???displayArticle.pubmedLink??? 29804838
???displayArticle.pmcLink??? PMC6046275
???displayArticle.link??? Cell
???displayArticle.grants??? [+]

Species referenced: Xenopus laevis
Genes referenced: shh smo

References [+] :
Alcedo, The Drosophila smoothened gene encodes a seven-pass membrane protein, a putative receptor for the hedgehog signal. 1996, Pubmed