Figure 3: FXII binding to the platelet surface is specific and zinc-dependent.

(A) The binding of FXII-FITC (100 nM) to resting platelets and platelets stimulated with 50 μM SFLLRN was measured by flow cytometry in the absence or presence of Zn²⁺. Each experiment was performed with 6 replicates, and representative scatter plots are shown here. (B) Binding of FXII-FITC (100 nM) to stimulated platelets in the presence of 10 μM Zn²⁺ and increasing molar equivalents of unlabeled FXII was measured by flow cytometry (representative plot from 3 independent experiments with 3 replicates for each condition). (C) Binding of FXII-FITC to stimulated platelets was measured in the presence or absence of 10 μM Zn²⁺ and with or without 30-minute preincubation with 0.2% sodium azide and 4 mg/ml 2-deoxy-D-glucose (2DDG), N=6 replicates, **P<0.0001 (D) FXII-FITC (100 nM) binding to stimulated washed platelets was recorded by flow cytometry at increasing concentrations of the indicated divalent metal cations (N=3 replicates per condition).