Browsing by Author "Hsieh, Chia-Fen"

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Stepped changes of monovalent ligand-binding force during ligand-induced clustering of integrin alpha(IIB)beta(3)
(2006-09-01)
Hsieh, Chia-Fen
;
Chang, Bo-Jui
;
Pai, Chyi-Huey
;
Chen, Hsuan-Yi
;
Tsai, Jin-Wu
Recent evidence demonstrated that conformational changes of the integrin during receptor activation affected its binding to extracellular matrix; however, experimental assessment of ligand-receptor binding following the initial molecular interaction has rarely been carried out at a single-molecule resolution. In the present study, laser tweezers were used to measure the binding force exerted by a live Chinese hamster ovary cell that expressed integrin alpha(IIb)beta(3) (CHO alpha(IIb)beta(3)), to the bead carrier coated with the snake venom rhodostomin that served as an activated ligand for integrin alpha(IIb)beta(3). A progressive increase of total binding force over time was noticed when the bead interacted with the CHO alpha(IIb)beta(3) cell; such an increase was due mainly to the recruitment of more integrin molecules to the bead-cell interface. When the binding strength exerted by a single ligand-receptor pair was derived from the "polyvalent" measurements, surprisingly, a stepped decrease of the "monovalent binding force" was noted (from 4.15 to 2.54 piconewtons (pN)); such decrease appeared to occur during the ligand-induced integrin clustering process. On the other hand, the mutant rhodostomin defective in clustering integrins exhibited only one (1.81 pN) unit binding strength.