Bone Morphogenetic Protein Receptors. SIGMA-ALDRICH. Bone Morphogenetic Protein Receptors
Bone morphogenetic protein (BMP) induces ectopic bone formation, and plays an important role in the development of the viscera. Ligand binding to its receptor induces the formation of a complex in which the Type II BMP receptor phosphorylates and activates the Type I BMP receptor. The Type I BMP receptor then propagates the signal by phosphorylating a family of signal transducers, the Smad proteins. Currently, eight Smad proteins have been cloned (Smad 1-7 and Smad 9). Upon phosphorylation by the BMP Type I receptor, Smad1 can interact with either Smad4 or Smad6. The Smad1-Smad6 complex is inactive; however, the Smad1-Smad4 complex triggers the expression of BMP responsive genes. The ratio between Smad4 and Smad6 in the cell can modulate the strength of the signal transduced by BMP.
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