| 背景资料 | Smads are a family of intracellular proteins that transmit transforming growth factor beta (TGF-beta) superfamily signals from the cell surface to the nucleus. The Smad family is divided into three subclasses: receptor regulated Smads, (Smads 1, 2, 3, 5 and 8); the common partner, (Smad4); and the inhibitory Smads, (Smads 6 and 7). The binding of TGF-beta or activin to their cognate receptor induces phosphorylation of Smads 2 and 3. The activated Smads associate with the common-mediator subunit, Smad4, and the heteromeric complex translocates into the nucleus to initiate transcription. Smad3, also known as Mothers Against Decapentaplegic homolog 3 (MADH3), shares 83% amino acid identity with Smad2, also known as Mothers Against Decapentaplegic homolog 2 (MADH2). Human Smad2 has 99% identity to mouse and rat Smad2. Human Smad3 has 99% identity to mouse and rat Smad3. |
