From Wikipedia, the free encyclopedia
TALIN is a high-molecular-weight cytoskeletal protein concentrated at regions of cell–substratum contact[1] and, in lymphocytes, at cell–cell contacts.[2][3] Talin is a ubiquitous cytosolic protein that is found in high concentrations in focal adhesions. It is capable of linking integrins to the actin cytoskeleton either directly or indirectly by interacting with vinculin and alpha-actinin.[4] Integrin receptors are involved in the attachment of adherent cells to extracellular matrices[5][6] and of lymphocytes to other cells. In these situations, talin codistributes with concentrations of integrins in the cell surface membrane.[7][8] Furthermore, in vitro binding studies suggest that integrins bind to talin, although with low affinity.[9] Talin also binds with high affinity to vinculin,[10] another cytoskeletal protein concentrated at points of cell adhesion.[11] Finally, talin is a substrate for the Ca2+-activated protease, calpain II,[12] which is also concentrated at points of cell-substratum contact.[13]
[edit] Talin Domains
Talin consists of a large C-terminal rod domain that contains bundles of α-alpha helices and an N-terminal FERM (band 4.1, ezrin, radixin, and moesin) domain with three subdomains: F1, F2, and F3.[14][15][16][17] The F3 subdomain of the FERM domain contains the highest affinity integrin-binding site for integrin β tails and is sufficient to activate integrins.[18]
Model of Talin-Induced
Integrin Activation.
[edit] Talin Activates Integrin αIIbβ3
A structure-function analysis reported recently[19] provides a cogent structural model (see top right) to explain talin-dependent integrin activation in three steps:
- ♦ (A) The talin F3 domain (surface representation; colored by charge), freed from its autoinhibitory interactions in the full-length protein, becomes available for binding to the integrin.
- ♦ (B) F3 engages the membrane-distal part of the β3-integrin tail (in red), which becomes ordered, but the α-β integrin interactions that hold the integrin in the low-affinity conformation remain intact.
- ♦ (C) In a subsequent step, F3 engages the membrane-proximal portion of the β3 tail while maintaining its membrane-distal interactions.
[edit] References
- ^ Burridge K, Connell L (1983). "A new protein of adhesion plaques and ruffling membranes". J. Cell Biol. 97 (2): 359–67. doi:10.1083/jcb.97.2.359. PMID 6684120.
- ^ Kupfer A, Singer SJ, Dennert G (1986). "On the mechanism of unidirectional killing in mixtures of two cytotoxic T lymphocytes. Unidirectional polarization of cytoplasmic organelles and the membrane-associated cytoskeleton in the effector cell". J. Exp. Med. 163 (3): 489–98. doi:10.1084/jem.163.3.489. PMID 3081676.
- ^ Burn P, Kupfer A, Singer SJ (1988). "Dynamic membrane-cytoskeletal interactions: specific association of integrin and talin arises in vivo after phorbol ester treatment of peripheral blood lymphocytes". Proc. Natl. Acad. Sci. U.S.A. 85 (2): 497–501. doi:10.1073/pnas.85.2.497. PMID 3124107.
- ^ Alan D. Michelson (2006). Platelets, Second Edition. Boston: Academic Press. ISBN 0-12-369367-5.
- ^ Hynes RO (1987). "Integrins: a family of cell surface receptors". Cell 48 (4): 549–54. doi:10.1016/0092-8674(87)90233-9. PMID 3028640.
- ^ Ruoslahti E, Pierschbacher MD (1987). "New perspectives in cell adhesion: RGD and integrins". Science 238 (4826): 491–7. doi:10.1126/science.2821619. PMID 2821619.
- ^ Chen WT, Hasegawa E, Hasegawa T, Weinstock C, Yamada KM (1985). "Development of cell surface linkage complexes in cultured fibroblasts". J. Cell Biol. 100 (4): 1103–14. doi:10.1083/jcb.100.4.1103. PMID 3884631.
- ^ Kupfer A, Singer SJ (1989). "The specific interaction of helper T cells and antigen-presenting B cells. IV. Membrane and cytoskeletal reorganizations in the bound T cell as a function of antigen dose". J. Exp. Med. 170 (5): 1697–713. doi:10.1084/jem.170.5.1697. PMID 2530300.
- ^ Horwitz A, Duggan K, Buck C, Beckerle MC, Burridge K (1986). "Interaction of plasma membrane fibronectin receptor with talin--a transmembrane linkage". Nature 320 (6062): 531–3. doi:10.1038/320531a0. PMID 2938015.
- ^ Burridge K, Mangeat P (1984). "An interaction between vinculin and talin". Nature 308 (5961): 744–6. doi:10.1038/308744a0. PMID 6425696.
- ^ Geiger B (1979). "A 130K protein from chicken gizzard: its localization at the termini of microfilament bundles in cultured chicken cells". Cell 18 (1): 193–205. doi:10.1016/0092-8674(79)90368-4. PMID 574428.
- ^ Fox JE, Goll DE, Reynolds CC, Phillips DR (1985). "Identification of two proteins (actin-binding protein and P235) that are hydrolyzed by endogenous Ca2+-dependent protease during platelet aggregation". J. Biol. Chem. 260 (2): 1060–6. PMID 2981831.
- ^ Beckerle MC, Burridge K, DeMartino GN, Croall DE (1987). "Colocalization of calcium-dependent protease II and one of its substrates at sites of cell adhesion". Cell 51 (4): 569–77. doi:10.1016/0092-8674(87)90126-7. PMID 2824061.
- ^ Chishti AH, Kim AC, Marfatia SM, Lutchman M, Hanspal M, Jindal H, Liu SC, Low PS, Rouleau GA, Mohandas N, Chasis JA, Conboy JG, Gascard P, Takakuwa Y, Huang SC, Benz EJ, Bretscher A, Fehon RG, Gusella JF, Ramesh V, Solomon F, Marchesi VT, Tsukita S, Tsukita S, Hoover KB (1998). "The FERM domain: a unique module involved in the linkage of cytoplasmic proteins to the membrane". Trends Biochem. Sci. 23 (8): 281–2. doi:10.1016/S0968-0004(98)01237-7. PMID 9757824.
- ^ García-Alvarez B, de Pereda JM, Calderwood DA, Ulmer TS, Critchley D, Campbell ID, Ginsberg MH, Liddington RC (2003). "Structural determinants of integrin recognition by talin". Mol. Cell 11 (1): 49–58. doi:10.1016/S1097-2765(02)00823-7. PMID 12535520.
- ^ Papagrigoriou E, Gingras AR, Barsukov IL, Bate N, Fillingham IJ, Patel B, Frank R, Ziegler WH, Roberts GC, Critchley DR, Emsley J (2004). "Activation of a vinculin-binding site in the talin rod involves rearrangement of a five-helix bundle". EMBO J. 23 (15): 2942–51. doi:10.1038/sj.emboj.7600285. PMID 15272303.
- ^ Rees DJ, Ades SE, Singer SJ, Hynes RO (1990). "Sequence and domain structure of talin". Nature 347 (6294): 685–9. doi:10.1038/347685a0. PMID 2120593.
- ^ Calderwood DA, Yan B, de Pereda JM, Alvarez BG, Fujioka Y, Liddington RC, Ginsberg MH (2002). "The phosphotyrosine binding-like domain of talin activates integrins". J. Biol. Chem. 277 (24): 21749–58. doi:10.1074/jbc.M111996200. PMID 11932255.
- ^ Wegener KL, Partridge AW, Han J, Pickford AR, Liddington RC, Ginsberg MH, Campbell ID (2007). "Structural basis of integrin activation by talin". Cell 128 (1): 171–82. doi:10.1016/j.cell.2006.10.048. PMID 17218263.
[edit] See also
[edit] External links
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Proteins of the cytoskeleton |
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| Microfilaments |
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| Intermediate filaments |
type 1 and 2 ( Cytokeratin, type I, type II) - type 3 ( Desmin, GFAP, Peripherin, Vimentin) - type 4 ( Internexin, Nestin, Neurofilament, Synemin, Syncoilin) - type 5 ( Lamin A, B)
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Transmembrane receptors: immune receptors |
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| Cytokine receptor |
Type I: Interleukins ( 2, 3, 4, 5, 6, 7, 9, 11, 12, 13, 15, 21, 23, 27), CSF receptors ( EPO, GM-CSF, G-CSF), GH, prolactin, Oncostatin M, Leukemia inhibitory factor - common subunits ( Common gamma chain, common beta chain, CSF2RB)
Type II: Interleukins (10, 20, 22, 28) - interferon (-α/β, -γ)
immunoglobulin superfamily: CSF1, C-kit, IL-1, IL-18
Tumor necrosis factor: CD27, CD30, CD40, CD120, Lymphotoxin β
Chemokines: IL-8 (α, β), CCR1,CXCR4
Other: IL-17, TGF-beta ( 1, 2)
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