UDP-Glucuronosyltransferase 1 Family, Polypeptide A1 (UGT1A1)，as known as GNT1 or UGT1，is a member of the UDP-glucuronosyltransferase (UGT) enzyme family, which plays a critical role in the metabolism of various compounds in the body. This enzyme catalyzes the conjugation of bilirubin, steroids, and other lipophilic compounds with glucuronic acid, facilitating their excretion from the body.The binding of UGT1A1 and Cytochrome P450 1A1 (CYP1A1) is particularly importantin the metabolism of drugs and xenobiotics, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human UGT1A1 and recombinant rat CYP1A1. Briefly, biotin-linked UGT1A1 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100μl were then transferred to CYP1A1-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 UGT1A1 and CYP1A1 was shown in Figure 1, the EC50?for this effect is 0.08ug/mL.