Crystal structure of a phosphorylated Smad2. Recognition of phosphoserine by the MH2 domain and insights on Smad function in TGF-beta signaling.Wu, J.W., Hu, M., Chai, J., Seoane, J., Huse, M., Li, C., Rigotti, D.J., Kyin, S., Muir, T.W., Fairman, R., Massague, J., Shi, Y.
(2001) Mol Cell 8: 1277-1289
- PubMed: 11779503
- DOI: https://doi.org/10.1016/s1097-2765(01)00421-x
- Primary Citation of Related Structures:
- PubMed Abstract:
Ligand-induced phosphorylation of the receptor-regulated Smads (R-Smads) is essential in the receptor Ser/Thr kinase-mediated TGF-beta signaling. The crystal structure of a phosphorylated Smad2, at 1.8 A resolution, reveals the formation of a homotrimer mediated by the C-terminal phosphoserine (pSer) residues. The pSer binding surface on the MH2 domain, frequently targeted for inactivation in cancers, is highly conserved among the Co- and R-Smads. This finding, together with mutagenesis data, pinpoints a functional interface between Smad2 and Smad4. In addition, the pSer binding surface on the MH2 domain coincides with the surface on R-Smads that is required for docking interactions with the serine-phosphorylated receptor kinases. These observations define a bifunctional role for the MH2 domain as a pSer-X-pSer binding module in receptor Ser/Thr kinase signaling pathways.
Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, NJ 08544, USA.