Coimmunoprecipitation of the interleukin-4Rα/GP Ibα subunit, filamin-1, and 14-3-3ζ.

The ability of the IL-4Rα/GP Ibα subunit to interact with other cytoplasmic proteins was investigated by immunoprecipitation. The immunopurified products were electrophoresed and analyzed by Western blotting using antibodies that recognize filamin-1 (A) or 14-3-3ζ (B). Shown is the resulting autoradiograph produced by the immunoreactive species. Lane 1, normal (wild-type) mouse platelet lysate (no immunoprecipitation); lane 2, immunoprecipiated platelet lysate from animals devoid of mouse GP Ibα but expressing the IL-4Rα transgene (Tg³³; GP Ibα^null); lane 3, same lystate as lane 2 but immunoprecipitated with a control IgG; lane 4, normal (wild-type) mouse platelet lysate immunoprecipitated with the anti–IL-4R mAb; lane 5, normal human platelet lysate (no immunoprecipitation).