The Drosophila smoothened Gene Encodes a Seven-Pass Membrane Protein, a Putative Receptor for the Hedgehog Signal

• Published in: Cell 1996-07, Vol.86 (2), p.221-232
• Main Authors: Alcedo, Joy, Ayzenzon, Marina, Von Ohlen, Tonia, Noll, Markus, Hooper, Joan E
• Format: Article
• Language: English
• Subjects: Animals; Base Sequence; Cell Membrane - chemistry; Cell Membrane - physiology; Cloning, Molecular; Drosophila; Drosophila - genetics; Drosophila Proteins; Female; Gene Expression Regulation, Developmental - physiology; Genes, Insect - genetics; GTP-Binding Proteins - genetics; Hedgehog Proteins; Immunohistochemistry; In Situ Hybridization; Male; Molecular Sequence Data; Phenotype; Proteins - physiology; Proto-Oncogene Proteins - genetics; Receptors, Cell Surface - genetics; Receptors, Cell Surface - physiology; Receptors, G-Protein-Coupled; Sequence Homology, Amino Acid; Signal Transduction - genetics; Smoothened Receptor; Wnt1 Protein
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/S0092-8674(00)80094-X

smoothened ( smo) is a segment polarity gene required for correct patterning of every segment in Drosophila. The earliest defect in smo mutant embryos is loss of expression of the Hedgehog-responsive gene wingless between 1 and 2 hr after gastrulation. Since smo mutant embryos cannot respond to exogenous Hedgehog (Hh) but can respond to exogenous Wingless, the Smo product functions in Hh signaling. Smo acts downstream of or in parallel to Patched, an antagonist of the Hh signal. The smo gene encodes an integral membrane protein with characteristics of G protein–coupled receptors and shows homology to the Drosophila Frizzled protein. Based on its predicted physical characteristics and on its position in the Hh signaling pathway, we suggest that smo encodes a receptor for the Hh signal.