Stepped changes of monovalent ligand-binding force during ligand-induced clustering of integrin alphaIIB beta3.
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.
Hsieh
Chia-Fen
CF
Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan.
Chang
Bo-Jui
BJ
Pai
Chyi-Huey
CH
Chen
Hsuan-Yi
HY
Tsai
Jin-Wu
JW
Yi
Yung-Hsiang
YH
Chiang
Yi-Ting
YT
Wang
Da-Wei
DW
Chi
Sien
S
Hsu
Long
L
Lin
Chi-Hung
CH
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
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