Xenbase Image ID: 159443

Figure 6. Structure-function analyses of Sox17-TCF-β-catenin interactions. (A) Sox17 interacts with TCF4 protein via its HMG domain. The left panel shows a schematic diagram of Sox17 deletions and point mutations. HMG mutant 1 carries a stringent mutation (G to R at amino acid 103), and HMG mutant 2 carries a more conservative mutation (M to A at amino acid 76). d1-367, now contains amino acids 1 to 367; d129-419, now contains amino acids 129 to 419. The right panel shows the interaction of in vitro-translated Sox17 mutant proteins (V5 tagged) with GST alone, TCF4-GST, or β-catenin (β-cat)-GST. (B) Identification of protein domains of TCF3 that mediate its interaction with Sox17. The left panel shows a schematic diagram of deletions of Xenopus TCF3. The right panel shows the interaction of the in vitro-translated S35-labeled TCF3 mutant proteins with His-tagged Xenopus Sox17β or Ni-agarose alone. (C) Sox17 requires interactions with both β-catenin and TCF/LEF to antagonize Wnt activity. COS cells were transfected with β-catenin(S37A) and TOP-flash alone or together with the Sox17 mutant forms, and TOP-flash activity was measured after 48 h. Error bars indicate standard errors of the means of results for replicate samples from at least three separate experiments. (D) Sox17 does not require transcriptional activity to antagonize Wnt activity. 293T cells were cotransfected with Sox17 and derived mutant forms and a Sox17 reporter plasmid (pH4X8-Luci). The transcriptional activity of Sox17 requires a functional DNA binding domain (HMG domain) and a functional transactivation domain (at the C terminus). While the Sox17 HMG mutant form carrying an M-to-A mutation is transcriptionally inactive, it still is able to interact with both TCF4 and β-catenin and antagonize Wnt activity. Error bars indicate standard errors of the means of results for replicate samples from two separate experiments. Image published in: Sinner D et al. (2007) Copyright © 2007. Image reproduced with permission of the Publisher, American Society for Cell Biology (ASCB). This is an Open Access article. Larger Image Printer Friendly View

Return to previous page