Multimerin 1 (MMRN1) is a secreted glycoprotein that consists of multiple subunits, forming a complex with a molecular weight of approximately 150 kDa. MMRN1 is a member of the multimerin family and it is mainly expressed in platelets and endothelial cells. MMRN1 plays an important role in maintaining vascular integrity, regulating clotting and inflammatory responses, among others. In addition, the binding of MMRN1 to Vitronectin (VTN) plays an important role in a variety of physiological and pathological processes, including cell adhesion, migration, blood coagulation, and cell signaling. Thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human MMRN1 and recombinant human VTN. Briefly, MMRN1 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to VTN-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-MMRN1 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 450/630 nm immediately. The binding activity of recombinant human MMRN1 and recombinant human VTN was shown in Figure 1, and this effect was in a dose dependent manner.