Adhesion-induced dephosphorylation of a 67-kD protein band. Washed, 32P-labeled human platelets were used to assess changes in phosphorylation caused either by adhesion to collagen and polylysine or by thrombin-induced aggregation as described in the Materials and Methods. Whole cells lysates from 1.5 × 107 platelets were analyzed by 12% SDS-PAGE full-size gels: “resting” refers to control unstimulated platelets; “effluent” refers to platelets that failed to adhere to collagen; “polylysine” refers to platelets adherent to polylysine; “collagen” represents platelets adherent to collagen; and “thrombin” refers to platelets aggregated by thrombin (1 U/mL). Molecular weight standards (in kilodaltons) are shown on the left, and the weights of some protein bands altered by adhesion are indicated on the right. An autoradiogram representative of six experiments is presented.
