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Static Adhesion Assay for the Study of Integrin Activation in T Lymphocytes
Published on: June 13, 2014
Modulation of Lck function through multisite docking to T cell-specific adapter protein.
Stine Granum1, Thorny Cesilie Bie Andersen, Morten Sørlie
1Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Box 1105, Blindern, N-0317 Oslo, Norway. stine.granum@medisin.uio.no
The Journal of Biological Chemistry
|June 11, 2008
Summary
T cell-specific adapter protein (TSAd) binds and phosphorylates Lck, modulating T cell receptor signaling. This interaction, involving multiple sites on TSAd, suggests TSAd competes for Lck, regulating its activity.
Area of Science:
- Immunology
- Molecular Biology
- Cell Signaling
Background:
- T cell-specific adapter protein (TSAd) is crucial for T cell receptor (TCR) signaling.
- TSAd interacts with Lck, a key kinase in TCR signaling pathways.
- Understanding these interactions is vital for deciphering T cell activation.
Purpose of the Study:
- To map and functionally evaluate Lck phosphorylation and interaction sites on TSAd.
- To elucidate the role of these interactions in modulating Lck activity and TCR signaling.
Main Methods:
- Site-directed mutagenesis to identify TSAd phosphorylation and binding sites.
- Biochemical assays to measure binding affinities between TSAd peptides and Lck domains.
- Analysis of TSAd phosphorylation in activated T cells.
Main Results:
- Lck phosphorylates three C-terminal tyrosines (Tyr280, Tyr290, Tyr305) on TSAd, serving as docking sites for Lck's SH2 domain.
- TSAd Tyr305 exhibits a 10-fold higher binding affinity for Lck SH2 than other sites.
- Efficient TSAd phosphorylation by Lck requires both Lck SH3-binding and SH2 domains on TSAd.
- TSAd-Lck interactions are essential for modulating proximal TCR signaling events.
- In activated T cells, 20-30% of TSAd is phosphorylated, with a TSAd:Lck ratio of approximately 1:1.
Conclusions:
- Lck binds TSAd prolines and interacts with phosphorylated C-terminal tyrosines.
- TSAd modulates Lck activity through multivalent interactions, potentially by competing with other Lck substrates.
- This mechanism highlights TSAd's role as a regulator of Lck function in T cells.
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