A 155-kD tyrosine phosphorylated protein is unrelated to p140 SHIP and coimmunoprecipitates with SHC from K562 lysates. (A) NP-40 lysates of K562 cells (10 × 106) were immunoprecipitated (IP) with rabbit antibodies to SHC or to mouse IgG (RIgG; which served as a control antibody). Immunoprecipitates were separated in 7.5% SDS-PAGE gels, transferred to Immobilon, and immunoblotted with the antibodies indicated on the left of each panel. Each immunoblot represents a reprobing of the same filter. Molecular weights (in kilodaltons) are indicated on the right side of each panel. Please note that the p140 SHIP polyclonal antibody used for blotting (8727) is directed against the carboxyl amino acids 1103-1192 of human SHIP. (B) NP-40 lysates (WCL; 50 μg) from M07, R10−, R10+, and K562 cell lines were separated by SDS-PAGE, transferred to Immobilon, and immunoblotted with p140 SHIP polyclonal antibody 5340 that is directed against amino acids 670-868 of p140 SHIP.
