Transferrin Receptor (TFR) , also known as cluster of differentiation 71 (CD71), is a type II transmembrane glycoprotein that plays a crucial role in the transport of iron into the cell. It binds to Transferrin (TRF), a carrier protein that transports iron in the blood, and facilitates the uptake of iron through endocytosis. This process is essential for many biological functions, including DNA synthesis and cell growth.Thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human TFR and recombinant chicken TRF. Briefly, biotin-linked TFR were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100μl were then transferred to TRF-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST 3 times and incubation with Streptavidin-HRP for 30min, then wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50µl stop solution to the wells and read at 450nm immediately. The binding activity of TFR and TRF was shown in Figure 1, the EC50 for this effect is 0.068ug/mL.