Smoothened, transmembrane domain (IPR035683)

Short name: SMO_7TM

Overlapping homologous superfamilies


Domain relationships


Smoothened (SMO) is a transmembrane G protein-coupled receptor that acts as the transducer of the hedgehog (HH) signaling pathway [PMID: 24148123]. SMO is activated by the hedgehog (HH) family of proteins acting on the 12-transmembrane domain receptor patched (PTCH), which constitutively inhibits SMO. Thus, in the absence of HH proteins, PTCH inhibits SMO signaling. On the other hand, binding of HH to the PTCH receptor activates its internalization and degradation, thereby releasing the PTCH inhibition of SMO. This allows SMO to trigger intracellular signaling and the subsequent activation of the Gli family of zinc finger transcriptional factors and induction of HH target gene expression (PTCH, Gli1, cyclin, Bcl-2, etc) [PMID: 9811578]. SMO is closely related to the frizzled (FZD) family of seven transmembrane-spanning proteins, which constitute a novel and separate family of G-protein coupled receptors [PMID: 15239825, PMID: 14977528].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.