Fibrinogen Beta Chain (FGB) is the beta subunit of the coagulation factor fibrinogen, which is a component of the blood clot. Following vascular injury, fibrinogen is cleaved by thrombin to form fibrin which is the most abundant component of blood clots. Studies have shown that fibrinogen can enhances expression of SELP in activated platelets via an ITGB3-dependent pathway. Thus a functional ELISA assay was conducted to detect the interaction of recombinant mouse FGB and recombinant human ITGb3. Briefly, FGB was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to ITGb3-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-FGB pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630nm immediately. The binding activity of recombinant mouse FGB and recombinant human ITGb3 was shown in Figure 1, the EC50 for this effect is 0.016 ug/mL.