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Proceedings Paper

Identification of stepped changes of binding affinity during interactions between the disintegrin rhodostomin and integrin alpha(IIb)beta(3) in living cells using optical tweezers
Author(s): Chia-Fen Hsieh; Bo-Jui Chang; Chyi-Huey Pai; Hsuan-Yi Chen; Sien Chi; Long Hsu; Jin-Wu Tsai; Chi-Hung Lin
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Paper Abstract

Integrin receptors serve as both mechanical links and signal transduction mediators between the cell and its environment. Experimental evidence demonstrates that conformational changes and lateral clustering of the integrin proteins may affect their binding to ligands and regulate downstream cellular responses; however, experimental links between the structural and functional correlations of the ligand-receptor interactions are not yet elucidated. In the present report, we utilized optical tweezers to measure the dynamic binding between the snake venom rhodostomin, coated on a microparticle and functioned as a ligand, and the membrane receptor integrin alpha(IIb)beta(3) expressed on a Chinese Hamster Ovary (CHO) cell. A progressive increase of total binding affinity was found between the bead and CHO cell in the first 300 sec following optical tweezers-guided contact. Further analysis of the cumulative data revealed the presence of "unit binding force" presumably exerted by a single rhodostomin-integrin pair. Interestingly, two such units were found. Among the measurements of less total binding forces, presumably taken at the early stage of ligand-receptor interactions, a unit of 4.15 pN per molecule pair was derived. This unit force dropped to 2.54 pN per molecule pair toward the later stage of interactions when the total binding forces were relatively large. This stepped change of single molecule pair binding affinity was not found when mutant rhodostomin proteins were used as ligands (a single unit of 1.81 pN per pair was found). These results were interpreted along with the current knowledge about the conformational changes of integrins during the "molecule activation" process.

Paper Details

Date Published: 18 October 2004
PDF: 10 pages
Proc. SPIE 5514, Optical Trapping and Optical Micromanipulation, (18 October 2004); doi: 10.1117/12.558653
Show Author Affiliations
Chia-Fen Hsieh, National Yang Ming Univ. (Taiwan)
Bo-Jui Chang, National Chiao-Tung Univ. (Taiwan)
Chyi-Huey Pai, Institute of Biomedical Sciences (Taiwan)
Hsuan-Yi Chen, National Central Univ. (Taiwan)
Sien Chi, National Chiao-Tung Univ. (Taiwan)
Long Hsu, National Chiao-Tung Univ. (Taiwan)
Jin-Wu Tsai, National Yang Ming Univ. (Taiwan)
Chi-Hung Lin, National Yang Ming Univ. (Taiwan)

Published in SPIE Proceedings Vol. 5514:
Optical Trapping and Optical Micromanipulation
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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