Fig. 7. Association of MAGI-3 with tyrosine-phosphorylated proteins. (A) SF763T cells treated with (+) or without (-) vanadate were immunoprecipitated using antibodies to MAGI-3 (MAGI-3 or M23), preimmune serum (PI) or anti-phosphotyrosine (PY). The immunocomplexes were separated on SDS gels and immunoblotted with anti-MAGI-3 (upper panel) or anti-phosphotyrosine (lower panel) antibodies, as indicated. The immunocomplexes from one set of samples were treated with alkaline phosphatase (MAGI-3 + AP) before immunoblotting. MAGI-3 was neither detected by anti-phosphotyrosine after immunoprecipitation with an anti-MAGI-3 antibody nor by anti-MAGI-3 immunoblotting after immunoprecipitation with anti-phosphotyrosine antibodies. The location of molecular weight markers is shown in kDa. (B) MAGI-3 is associated with different tyrosine-phosphorylated proteins in several cell lines. MAGI-3 was immunoprecipitated from untreated (-) or vanadate-treated (+) SF763T and C6 glioblastoma cells or Caco2 colon carcinoma cells, followed by immunoblotting with anti-phosphotyrosine (lower panel) or anti-MAGI-3 (upper panel) antibodies.