Xenbase Image ID: 159441

Figure 4. Sox17 forms a stable, trimeric complex with TCF/LEF and β-catenin proteins. (A) Sox17 interacts with TCF3, TCF4, and LEF proteins. Sox17-GST beads pulled down in vitro-translated, V5 epitope-tagged TCF4, TCF3, and LEF1, and GST beads did not. (B) The interaction between Sox17 and β-catenin is enhanced in the presence of TCF4. Sox17 or TCF4 independently bound to β-catenin-GST beads but not to GST beads alone (panels 1 and 2). The binding of Sox17 to β-catenin-GST beads was enhanced in the presence of TCF4 (compare the ratios of input to bound Sox17 in the presence and absence of TCF4 [lanes marked by *]). β-catenin-interacting proteins were analyzed by Western blotting with an anti-V5 antibody. (C) The interaction between β-catenin (β-cat) and TCF3 is stabilized by Sox17 and requires a Sox17-β-catenin interaction. In vitro-translated, S35-labeled TCF3 protein (input) was incubated with β-catenin (myc tagged) alone or with increasing concentrations of purified His-tagged Xenopus Sox17β or His-tagged Xenopus Sox17 consisting of amino acids 1 to 150, which removed the β-catenin interaction domain (ΔC Sox17). β-catenin and its associated proteins were precipitated with an anti-myc antibody, and TCF3 protein was analyzed by SDS-PAGE and autoradiography. IP, immunoprecipitate. (D and E) Under high-stringency conditions, Sox17-GST beads would not efficiently pull down β-catenin. However, in the presence of TCF4 (D) or TCF3 (E), Sox17 was able to pull down β-catenin. This interaction depends on the β-catenin interaction domain of TCF3, which is deleted in the N terminus-lacking TCF3 protein (ΔN TCF3). +, present; −, absent. 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

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