Common SMAD (co-SMAD) is the coactivator and mediator of signal transduction by TGF-beta (transforming growth factor). Component of the heterotrimeric SMAD2/SMAD3-SMAD4 complex that forms in the nucleus and is required for the TGF-mediated signaling. Promotes binding of the SMAD2/SMAD4/FAST-1 complex to DNA and provides an activation function required for SMAD1 or SMAD2 to stimulate transcription. Component of the multimeric SMAD3/SMAD4/JUN/FOS complex which forms at the AP1 promoter site; required for syngernistic transcriptional activity in response to TGF-beta. May act as a tumor suppressor.
Specificity
Natural and recombinant Bovine Mothers against decapentaplegic homolog 4
Subcellular Location
Cytoplasm Nucleus Cytoplasmic in the absence of ligand. Migrates to the nucleus when complexed with R-SMAD.
Monomer (By similarity). Heterotrimer; with a C-terminally phosphorylated R-SMAD molecule and to form the transcriptionally active SMAD2/3-SMAD4 complex (By similarity). Found in a ternary complex composed of SMAD4, STK11/LKB1 and STK11IP. Interacts with ATF2, COPS5, DACH1, MSG1, SKI, STK11/LKB1, STK11IP and TRIM33. Associates with ZNF423 or ZNF521 in response to BMP2 leading to activate transcription of BMP target genes. Interacts with USP9X. Interacts with RBPMS. Interacts with WWTR1 (via coiled-coil domain). Interacts with CITED1 and CITED2.