Tachykinin 4 (TAC4) , as known as ESTAC4, EK, HK-1, HK1, PPT-C, is a member of the tachykinin neuropeptide family.TAC4 protein participates in the regulation of blood pressure and is involved in processes such as the negative regulation of systemic arterial blood pressure.It is also associated with the inflammatory response and may play a role in promoting or regulating inflammation. Besides,TAC4 can initiate a series of intracellular signaling pathways by binding to receptors,such as Tachykinin Receptor 2 (TACR2) . Thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human TAC4 and recombinant rat TACR2.Briefly, biotin-linked TAC4 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100μl were then transferred to TACR2-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 TAC4 and TACR2 was shown in Figure 1, the EC50 for this effect is 0.40ug/mL.