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Crystal Structure of the R11R12 Domains of Talin
Structural highlights
FunctionTLN1_MOUSE Probably involved in connections of major cytoskeletal structures to the plasma membrane. High molecular weight cytoskeletal protein concentrated at regions of cell-substratum contact and, in lymphocytes, at cell-cell contacts. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe adaptor protein talin serves both to activate the integrin family of cell adhesion molecules and to couple integrins to the actin cytoskeleton. Integrin activation has been shown to involve binding of the talin FERM domain to membrane proximal sequences in the cytoplasmic domain of the integrin beta-subunit. However, a second integrin-binding site (IBS2) has been identified near the C-terminal end of the talin rod. Here we report the crystal structure of IBS2 (residues 1974-2293), which comprises two five-helix bundles, "IBS2-A" (1974-2139) and "IBS2-B" (2140-2293), connected by a continuous helix with a distinct kink at its center that is stabilized by side-chain H-bonding. Solution studies using small angle x-ray scattering and NMR point to a fairly flexible quaternary organization. Using pull-down and enzyme-linked immunosorbent assays, we demonstrate that integrin binding requires both IBS2 domains, as does binding to acidic phospholipids and robust targeting to focal adhesions. We have defined the membrane proximal region of the integrin cytoplasmic domain as the major binding region, although more membrane distal regions are also required for strong binding. Alanine-scanning mutagenesis points to an important electrostatic component to binding. Thermal unfolding experiments show that integrin binding induces conformational changes in the IBS2 module, which we speculate are linked to vinculin and membrane binding. Structural determinants of integrin binding to the talin rod.,Gingras AR, Ziegler WH, Bobkov AA, Joyce MG, Fasci D, Himmel M, Rothemund S, Ritter A, Grossmann JG, Patel B, Bate N, Goult BT, Emsley J, Barsukov IL, Roberts GC, Liddington RC, Ginsberg MH, Critchley DR J Biol Chem. 2009 Mar 27;284(13):8866-76. Epub 2009 Jan 27. PMID:19176533[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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