Smad Proteins in TGF-Beta Signaling
Living reference work entry
The Smad proteins are a family of structurally related molecules which perform a pivotal function in the transforming growth factor-β (TGF-β) superfamily intracellular cascade. This cytokine superfamily includes TGF-β, activins, and bone morphogenetic proteins (BMP) and regulates a broad scale of biological responses, including cell fate and extracellular matrix production. TGF-β superfamily members signal through heteromeric complexes of transmembrane type I and type II serine/threonine kinase receptors. Upon ligand binding, type II receptor phosphorylates type I receptor, thus activating its kinase. The activated type I receptor then propagates signals to downstream targets such as the Smad proteins. Smads (for Sma and Mad proteins from Caenorhabditis elegans and Drosophila, respectively) are currently divided into three classes:
The receptor-activated Smads (R-Smads) transiently interact and become phosphorylated by specific activated type I receptor. In mammals, Smad1,...
KeywordsBone Morphogenetic Protein Adenomatous Polyposis Coli Smad Protein Bone Morphogenetic Protein Signaling Heteromeric Complex
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