Apolipoprotein C-III also known as apo-CIII, and apolipoprotein C3, is a glycoprotein (consisting of 79 amino acids) that is synthesized principally in the liver. APOC3 is a surface component of chylomicrons, very low density lipoproteins, and high densityl ipoprotein and it has been recently recognized as a polyhedric factor which may regulate several pathways beyond lipid metabolism by influencing cardiovascular, metabolic, and neurological disease risk. Besides, Apolipoprotein H (APOH) has been identified as an interactor of APOC3, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human APOC3 and recombinant human APOH. Briefly, biotin-linked APOC3 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to APOH-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 50 µl stop solution to the wells and read at 450 nm immediately. The binding activity of recombinant human APOC3 and recombinant human APOH was shown in Figure 1, the EC50 for this effect is 8.5 ug/mL.