Characterization of exocyst expression, association, posttranslational modification, and movement in EXOC3 KO platelets. (Ai) Representative immunoblots of exocyst complex components and platelet secretory markers from human and murine (WT and EXOC3 KO) platelets are shown. (Aii) Densitometric analysis of relative murine protein abundance expressed as a KO:WT ratio after loading adjustment. (B) Washed platelets (5 × 10⁸/mL) from WT and KO platelets were rested or stimulated with 5 µg/mL CRP for 5 minutes, lysed, and subjected to coimmunoprecipitation analysis of exocyst components with an EXOC2 antibody. Immunoprecipitation inputs were monitored for exocyst expression and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as loading control. (Ci) Lysates from WT and KO platelets (5 × 10⁸/mL) treated with 5 µg/mL CRP for indicated times (minutes) were subject to phos-tag immunoblot analysis of EXOC3, 4 and 7. Densitometric analysis of changes in phosphorylated EXOC4 (Cii) and EXOC7 (Ciii) (pEXOC4/pEXOC7) were measured. (D) After stimulation of washed platelets (1 × 10⁹/mL) with 5 µg/mL CRP for indicated times (minutes), platelet proteins were separated into soluble and particulate fractions and analyzed for exocyst expression and various “control” proteins for the respective fractions. Data are presented as the mean ± standard error of the mean. n = 5 (A); n = 3 (B-D). *P < .05, **P < .01, ***P < .001 vs WT (A), unstimulated sample (Cii-iii), or as indicated. IgG, immunoglobulin G; ns, not significant.