Smoothened (E6Z5T) Rabbit mAb #92981

Smoothened is a 7-pass transmembrane G protein-coupled receptor that functions as a key transmembrane transducer of Hedgehog signaling (1). The primary function of Smoothened is to regulate the activity of GLI-family transcription factors (GLI1-3). In the canonical (mammalian) Hedgehog signaling pathway, Smoothened activity is constitutively repressed by the 12-pass transmembrane receptor Patched (PTCH1). PTCH1 represses Smoothened activity by controlling the availability of cholesterol, which serves as a second messenger agonist for Smoothened (2). This repression results in the association of GLI proteins with the STK36/SUFU protein complex, promoting GLI protein cleavage and nuclear translocation of “repressor” GLI protein fragments that suppress target gene transcription (1). Binding of Hedgehog ligands inactivates the PTCH1 receptor, resulting in the derepression of Smoothened. Active Smoothened promotes the release of GLI proteins from the STK36/SUFU protein complex, enabling cytoplasmic-to-nuclear translocation of full-length GLI proteins that activate target gene expression. The Hedgehog signaling pathway regulates cell fate, embryonic patterning, and postnatal tissue repair, but is generally quiescent in healthy postnatal tissues. However, research studies have shown that ectopic activation of the pathway (e.g., through aberrant Smoothened activity) can be oncogenic, making Smoothened and other components of the Hedgehog signaling pathway attractive targets for therapeutic intervention in some cancer types (3-5).