The K499E mutation affects the interaction of MAGI-1 with NET1 but does not alter its subcellular localization. (A) HEK293 cells were transfected with 3 μg of the FLAG-tagged MAGI-1 plasmids together with 5 μg of MYC-tagged mNET1, as indicated. After 24 h, cells were extracted and immunoprecipitated using anti-MYC antibody. NET1-bound MAGI-1 was then detected by Western blotting using anti-FLAG antibody. (B) HEK293 cells were transfected with 3 μg of wild-type or mutant MAGI-1 expression plasmids together with 5 μg of HA-tagged β-catenin. After 24 h, cell extracts were immunoprecipitated using anti-FLAG antibody-conjugated agarose beads, and MAGI-1-bound β-catenin was then detected by Western blotting using anti-HA antibody. The arrow indicates the position of the HA-tagged β-catenin in the top panel. (C) U2OS cells were transfected with the FLAG-tagged MAGI-1 constructs, and after 24 h the cells were fixed and incubated with anti-FLAG antibody to detect the MAGI-1 pattern of expression. Arrows indicate sites of MAGI-1 junctional accumulation.