Tyrosine phosphorylation in CRP-stimulated wild-type andlyn^−/−platelets.

(A) Antiphosphotyrosine immunoblots show whole-platelet tyrosine phosphorylation stimulated by CRP (1.0 μg/mL) from 20 to 180 seconds in wild-type and lyn^−/−platelets. Regions known to comigrate with Syk (70-80 kd), LAT (36-38 kd), and FcRγ chain (14-16 kd) are indicated. (B) Immunoprecipitates of Syk (i) and PLCγ2 (ii) immunoblotted with antiphosphotyrosine mAb in wild-type and lyn^−/−platelets at 30 and 180 seconds. Results are representative of 4 experiments. Wild-type and knockout samples were obtained from experiments run in parallel. Results shown in both panels are from samples resolved on the same gel and are from the same exposure on the same film.