Using optical tweezers to investigate the specific single-interaction between apoA-I molecule and ABCA1 on living cells

We carry out in situ single-molecule measurements of the specific interaction between apolipoprotein A-I （apoA-I） and ATP binding cassette transporter A1 （ABCA1） on THP-1 cells. Single-molecule force spectroscopy shows that similar to normal apoA-I, the dysfunctional apoA-I from diabetes patients interacts with ABCA1 via two different binding sites on the cells. The strength of dysfunctional apoA-I binding to a high-capacity binding site is 26.5±4.9 pN. The minor direct apoA-I/ABCA1 binding strength is 56.7±4.1 pN. These results facilitate a pathological understanding of the mechanisms that underlie the specific interaction of aDoA-I and ABCA1 at the single-molecule level.