Observing the dynamic variation of the binding force between rhodostomin ligand and integrin alpha (Ⅱb) beta (3) receptor using a photonic force microscope

摘要

The conformational change of integrin α_(Ⅱb)β_3 plays an important role hi clot formation. However, the correlation between the structure and the function of integrin α_(Ⅱb)β_3 in interacting with its ligand is still not clear. In this report, we focus on the dynamic variation of the binding between integrin α_(Ⅱb)β_3 and its ligand, rhodostomin by using a photonic force microscopy (PFM). The PFM is used to trap a rhodostomin-coated bead and, then, shift it to bind a surrounding CHO α_(Ⅱb)β_3 cell. Meanwhile, it tracks, with a resolution of 1MHz, the Brownian fluctuations of the trapped bead. Theoretically, the smaller the amplitude of the Brownian fluctuations, the stronger the stiffness of the binding force between the rhodostomin and the CHO α_(Ⅱb)β_3 cell. Experimentally, a significant decrease of the Brownian fluctuations was observed during the interval between the 360th seconds and the 400th seconds after the trapped rhodostomin-coated bead contacted an integrin-expressed CHO α_(Ⅱb)β_3 cell. This observation reveals that it takes the rhodostomin 360 seconds to seek the correct position to bind to the integrin α_(Ⅱb)β_3. After 400 seconds, the rhodostomin has bound rigidly with the integrin α_(Ⅱb)β_3- We presume that the integrin α_(Ⅱb)β_3 has reached its final stage of conformational change.