title: Stepped changes of monovalent ligand-binding force during ligand-induced clustering of integrin alphaIIB beta3.
abstract: 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 alphaIIb beta3 (CHO alphaIIb beta3), to the bead carrier coated with the snake venom rhodostomin that served as an activated ligand for integrin alphaIIb beta3. A progressive increase of total binding force over time was noticed when the bead interacted with the CHO alphaIIb beta3 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.
authors.affiliation: Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chia-Fen
authors.initials: CF
authors.lastname: Hsieh
authors.forename: Bo-Jui
authors.initials: BJ
authors.lastname: Chang
authors.forename: Chyi-Huey
authors.initials: CH
authors.lastname: Pai
authors.forename: Hsuan-Yi
authors.initials: HY
authors.lastname: Chen
authors.forename: Jin-Wu
authors.initials: JW
authors.lastname: Tsai
authors.forename: Yung-Hsiang
authors.initials: YH
authors.lastname: Yi
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Chiang
authors.forename: Da-Wei
authors.initials: DW
authors.lastname: Wang
authors.forename: Sien
authors.initials: S
authors.lastname: Chi
authors.forename: Long
authors.initials: L
authors.lastname: Hsu
authors.forename: Chi-Hung
authors.initials: CH
authors.lastname: Lin
mesh_terms: D000818:Animals; D016466:CHO Cells; D002138:Calibration; D002448:Cell Adhesion; D006224:Cricetinae; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D008024:Ligands; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000737:chemistry*; D010980:Platelet Membrane Glycoproteins / Q000737:chemistry; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D008024:Ligands; D010455:Peptides; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D010980:Platelet Membrane Glycoproteins; D011994:Recombinant Proteins; C072026:rhodostomin; D051416:Focal Adhesion Protein-Tyrosine Kinases