Anti-Smad2/3 Antibody, clone C4T, rabbit monoclonal

Smad proteins are regulators of transcription which transduce signals from TGFbeta Receptors. Smad proteins homotrimerize, and when activated, two distinct homotrimers assemble into a heterosextamer. Smad proteins fall into three classes. The receptor-regulated Smad proteins, Smad 1, 2, 3, 5, and 9 couple to specific receptors and are phosphorylated by those receptors. Phosphorylated receptor-regulated Smad proteins then bind to a co-Smad, such as Smad4/DPC4, and the complex moves to the nucleus where it associates with FAST-1 to stimulate target gene transcription. A third class of Smad proteins is the inhibitory group of Smad 6, 7, 8. Smad proteins have Mad-homology domains 1 and 2 (MH1 and MH2). MH1 domains are involved in DNA binding, while MH2 domains function in homotrimerization, receptor interaction and phosphorylation. Smad 4 mutations are frequently found in cancer, all of which cluster to the MH1 and MH2 domains of the protein. Those in the MH2 domain affect the ability of the protein to homotrimerize. The phosphorylation of Smad proteins is the regulatory signal in their activation, and can be monitored by the use of phosphorylation state-specific antibodies.