| APC (adenomatous polyposis coli) is a multifunctional tumor suppressor discovered by Polakis and Vogelstein. It not only affect the cell development by involving in the Wnt-signaling, but also has functions in the cell migration,chromosome seperation and neuron differentiation. Truckted APC often keep its N terminal, including Armadillo(ARM) domain, it's a very crucial part for for Wnt signaling transduction, and it also can activate Asef(APC-stimulated guanine nucleotide exchange factor), then activate Cdc42, and regulate the cell adhesion and migration.Although we have studied APC for more than 20 years, yet we still know little about its structure. In this study, we take use of X-ray crystal diffraction way and after a lot of hard work, we finally solve the structur characteristics of APC-PreARM-ARM (303-739)/Asef-ABR-SH3 (170-271) complex, and then determined its interaction characteristics between them, establishing the basis of studying cell adhesion and migration.I-Smads are a kind of key negative regulatory factors of TGF-βsignaling, including Smad6 and Smad7, Smad7 is mainly responsible for the signal transduction mediated by type I TGF-βreceptor, according to some report, this is because the NTD of Smad7 can bridge E3 ubiquitin ligase Smurf2 and the E2 ubiquitin-conjugating enzyme UbcH7 together. However we still didn't know their structure very well, and this greatly limite our knowledge about its fuctions in the cell.In this study, we tested the interaction between Smad7-NTD and UbcH7 in vitro, but unfortunately, we didn't see any binding between them. And we also conducted in-depth study for the Smad7-NTD. |
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