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1 Cancer Center, Burnham Institute for Medical Research, La Jolla, California 92037, USA
2 Department of Developmental and Cell Biology, University of California, Irvine, California 92697, USA
(RECEIVED January 29, 2007; FINAL REVISION March 1, 2007; ACCEPTED March 1, 2007)
Tensin is a cytoskeletal protein that links integrins to the actin cytoskeleton at sites of cell-matrix adhesion. Here we describe the crystal structure of the phosphotyrosine-binding (PTB) domain of tensin1, and show that it binds integrins in an NPxY-dependent fashion. Alanine mutagenesis of both the PTB domain and integrin tails supports a model of integrin binding similar to that of the PTB-like domain of talin. However, we also show that phosphorylation of the NPxY tyrosine, which disrupts talin binding, has a negligible effect on tensin binding. This suggests that tyrosine phosphorylation of integrin, which occurs during the maturation of focal adhesions, could act as a switch to promote the migration of tensinintegrin complexes into fibronectin-mediated fibrillar adhesions.
Keywords: structure/function studies; crystallography; calorimetry; mutagenesis (site-directed and general); docking proteins; surface plasmon resonance
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