CK2 interacts with occludin. A) HEK-293 cells were transiently transfected with FLAG-occludin and HA-CK2α and myc-CK2β as indicated, and after 24 h cells were lysed. Co-immunoprecipitations were performed with anti-FLAG M2 antibody and protein complexes were analyzed by SDS-PAGE and Western blotting with anti-HA antibody. Lysate controls are shown. B) Purified recombinant GST-fusion proteins of the occludin C-terminal cytoplasmic domain and deletion constructs thereof were incubated with recombinant CK2 protein and protein complexes were pulled down with GSH-agarose beads to show a direct interaction. After analysis by SDS-PAGE and Western blotting binding of CK2 was detected with an anti-CK2α antibody. Equal amounts of GST-fusion proteins were pulled down with GSH beads as shown in the lower panel. ** indicates heavy chain, and * indicates light chain of the precipitating antibody. The presented figures are representatives of at least three independent experiments.