SMAD3 Protein, Human/Mouse/Rat (GST)

The SMAD3 protein serves as a receptor-regulated SMAD (R-SMAD), functioning as an intracellular signal transducer and transcriptional modulator activated by TGF-beta and activin type 1 receptor kinases. It binds the TRE element in the promoter region of genes regulated by TGF-beta, and upon forming the SMAD3/SMAD4 complex, activates transcription. Additionally, SMAD3 can form a SMAD3/SMAD4/JUN/FOS complex at the AP-1/SMAD site to regulate TGF-beta-mediated transcription. This protein plays a role in wound healing, potentially modulating the growth and migration of primary keratinocytes and altering TGF-mediated chemotaxis of monocytes, with its impact on wound healing being hormone-sensitive. SMAD3 also acts as a regulator of chondrogenesis and osteogenesis and inhibits the early healing of bone fractures. Furthermore, it positively regulates PDPK1 kinase activity by stimulating its dissociation from the negative regulator 14-3-3 protein YWHAQ. The protein exists as a monomer in the absence of TGF-beta and forms a homooligomer in its presence, or a heterotrimer with C-terminally phosphorylated SMAD2 or SMAD3 and SMAD4 to form the transcriptionally active SMAD2/SMAD3-SMAD4 complex. SMAD3 interacts with various proteins involved in diverse cellular processes, including signal transduction, transcriptional regulation, ubiquitination, and protein-protein interactions.