LCAT (Phosphatidylcholine-sterol acyltransferase) is an enzyme in the extracellular metabolism of plasma lipoproteins, which converts cholesterol and phosphatidylcholines (lecithins) to cholesteryl esters and lysophosphatidylcholines. It is reported that APOA1 (Apolipoprotein A-I) acts as a cofactor for the LCAT. Thus, a binding ELISA assay was conducted to detect the association of LCAT with APOA1. Briefly, recombinant rat LCAT were diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100uL were then transferred to APOA1-coated microtiter wells and incubated for 2h at 37°C. Wells were washed with PBST and incubated for 1h with anti-LCAT pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 3 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37°C. Finally, add 50μL stop solution to the wells and read at 450nm immediately. The binding activity of LCAT with APOA1 was shown in Figure 1 and this effect was in a dose dependent manner.