Fatty Acid Binding Protein 2, Intestinal (FABP2)?is a cytoplasmic protein highly expressed in enterocytes, responsible for intracellular trafficking of dietary long-chain fatty acids (FAs). It enhances FA uptake, solubilization, and transport to the endoplasmic reticulum for triglyceride synthesis and chylomicron assembly. FABP2 also modulates lipid metabolism by regulating peroxisome proliferator-activated receptor (PPAR) signaling. Genetic variants are linked to insulin resistance and cardiovascular risk due to altered FA metabolism.FABP2 can interact with APOA1 to promote the transfer of lipids to newborn high-density lipoprotein (HDL) particles, promote cholesterol efflux and HDL maturation.Thus a functional ELISA assay was conducted to detect the interaction of recombinant mouse FABP2 and recombinant human APOA1. Briefly, FABP2 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to APOA1-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-FABP2 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 450/630nm immediately. The binding activity of recombinant mouse FABP2 and recombinant human APOA1 was shown in Figure 1, and this effect was in a dose dependent manner.