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C-terminal Mad Homology 2 (MH2) domain in receptor regulated SMADs The MH2 domain is located at the C-terminus of the SMAD (small mothers against decapentaplegic) family of proteins, which are signal transducers and transcriptional modulators that mediate multiple signaling pathways. The MH2 domain is responsible for type I receptor interaction, phosphorylation-triggered homo- and hetero-oligomerization, and transactivation. It is negatively regulated by the N-terminal MH1 domain. Receptor regulated SMADs (R-SMADs) include SMAD1, SMAD2, SMAD3, SMAD5 and SMAD9. SMAD1 plays an essential role in bone development and postnatal bone formation through activation by bone morphogenetic protein (BMP) type 1 receptor kinase. SMAD2 regulates multiple cellular processes, such as cell proliferation, apoptosis and differentiation, while SMAD3 modulates signals of activin and TGF-beta. SMAD5 is involved in BMP signal modulation, possibly playing a role in the pathway involving inhibition of hematopoietic progenitor cells by TGF-beta. SMAD9 (also known as SMAD8) can mediate the differentiation of mesenchymal stem cells into tendon-like cells by inhibiting the osteogenic pathway. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",