1u7v
Crystal Structure of the phosphorylated Smad2/Smad4 heterotrimeric complex
Structural highlights
FunctionSMAD2_HUMAN Receptor-regulated SMAD (R-SMAD) that is an intracellular signal transducer and transcriptional modulator activated by TGF-beta (transforming growth factor) and activin type 1 receptor kinases. Binds the TRE element in the promoter region of many genes that are regulated by TGF-beta and, on formation of the SMAD2/SMAD4 complex, activates transcription. May act as a tumor suppressor in colorectal carcinoma. Positively regulates PDPK1 kinase activity by stimulating its dissociation from the 14-3-3 protein YWHAQ which acts as a negative regulator.[1] [2] [3] [4] [5] Evolutionary Conservation![]() Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe formation of protein complexes between phosphorylated R-Smads and Smad4 is a central event in the TGF-beta signaling pathway. We have determined the crystal structure of two R-Smad/Smad4 complexes, Smad3/Smad4 to 2.5 angstroms, and Smad2/Smad4 to 2.7 angstroms. Both complexes are heterotrimers, comprising two phosphorylated R-Smad subunits and one Smad4 subunit, a finding that was corroborated by isothermal titration calorimetry and mutational studies. Preferential formation of the R-Smad/Smad4 heterotrimer over the R-Smad homotrimer is largely enthalpy driven, contributed by the unique presence of strong electrostatic interactions within the heterotrimeric interfaces. The study supports a common mechanism of Smad protein assembly in TGF-beta superfamily signaling. Structural basis of heteromeric smad protein assembly in TGF-beta signaling.,Chacko BM, Qin BY, Tiwari A, Shi G, Lam S, Hayward LJ, De Caestecker M, Lin K Mol Cell. 2004 Sep 10;15(5):813-23. PMID:15350224[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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