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The cytosolic protein talin induces an intermediate affinity integrin alphaLbeta2
Yan-Feng Li1, Ren-Hong Tang, Kia-Joo Puan
1School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551.
The Journal of Biological Chemistry
|June 27, 2007
Summary
Talin induces an intermediate affinity state of integrin alphaLbeta2, mediating T cell adhesion and migration. This intermediate affinity allows binding to ICAM-1 but not ICAM-3 without additional activation.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Integrin alphaLbeta2 is crucial for immune cell function, mediating adhesion and migration.
- Inside-out signaling alters alphaLbeta2 affinity states, impacting ligand binding.
- Talin connects alphaLbeta2 to the actin cytoskeleton and is known to activate its ligand binding.
Purpose of the Study:
- To determine if talin promotes an intermediate or high affinity state of integrin alphaLbeta2.
- To investigate the specific ligand-binding properties of talin-induced alphaLbeta2.
- To assess the functional consequences of talin-mediated alphaLbeta2 activation on T cell adhesion and migration.
Main Methods:
- Utilized transfectants and primary T cells.
- Investigated alphaLbeta2 affinity states using ICAM-1 and ICAM-3 binding assays.
- Assessed T cell adhesion and migration on immobilized ICAMs.
Main Results:
- Talin induced an intermediate affinity state of alphaLbeta2.
- This intermediate affinity state showed constitutive adhesion to ICAM-1 but not ICAM-3.
- Adhesion to ICAM-3 required an additional exogenous activating agent.
- Talin-induced intermediate affinity alphaLbeta2 supported T cell adhesion and migration on immobilized ICAMs.
Conclusions:
- Talin promotes an intermediate affinity state of integrin alphaLbeta2.
- The talin-induced intermediate affinity state differentially binds ICAM-1 and ICAM-3.
- This talin-mediated activation is sufficient for T cell adhesion and migration on ICAMs.
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