α-Granule proteins of platelets, plasma, and serum in WT and SG−/− mice. (A) Immunoblot of platelet PF4. Proteins from 4 × 107 platelets per sample (each sample represents a single mouse) were subjected to SDS-PAGE, followed by immunoblot analysis for PF4. The top panel in panel A shows Coomassie staining of the same samples as in the lower panel; note the actin band. (B) Immunoblot of NAP-2. Proteins from equal numbers of WT and KO platelets were applied to the gel. NAP-2 was identified by immunoblotting (bottom panel). The same blot was probed with antiactin (top panel). Detection was by ECL. (C) Immunoblot of PDGF. Aliquots of same samples shown in panel B were applied to the gels. Labeling of PDGF was detected by ECL. (D) ELISA for quantitation of PF4 in plasma and serum. Half of the blood sample from each mouse was anticoagulated (plasma) and half was allowed to clot (serum). Two WT and 2 SG−/− mice were tested.
