Figure 1.

β-Trcp forms a complex with β-catenin and Axin in vivo. (A and B) Association between β-Trcp and β-catenin. (A) Immunoprecipitation of β-Trcp^myc with an anti-myc antibody. Embryo extracts were from stage 9 embryos expressing β-catenin, β-catenin (S→A), or β-Trcp^myc alone or in combination. The precipitates were examined for β-catenin (Upper) and for β-Trcp^myc (Lower). A longer exposure revealed that β-Trcp^myc also coprecipitated endogenous β-catenin (data not shown). (B) Immunoprecipitation of β-catenin using the same embryo extracts as in A. The precipitates were examined for β-Trcp^myc (Upper) and for β-catenin (Lower). Endogenous β-catenin is seen in lanes 1 and 4. RNA injected per embryo: 1 ng each for β-catenin, β-catenin (S→A), and β-Trcp^myc. (C and D) A complex formation between β-Trcp and Axin mediated by β-catenin. (C) Immunoprecipitation of β-Trcp^myc. The extracts were from stage 9 embryos expressing β-Trcp^myc plus Axin^Flag in the presence or absence of β-catenin or β-catenin (S→A). The precipitates were examined for β-catenin (Top), Axin^Flag (Middle), and β-Trcp^myc (Bottom). (D) Immunoprecipitation of Axin^Flag using the same extracts as in C. The precipitates were examined for β-Trcp^myc (Top), β-catenin (Middle), and Axin^Flag (Bottom). RNA injected per embryo: same as in A and B except 2 ng for Axin^Flag.