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| Subject Categories: Cell & Tissue Architecture |
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| The EMBO Journal
(2006) 25, 1184–1195, doi:10.1038/sj.emboj.7601019 Published online 2 March 2006 |
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| Mammalian twinfilin sequesters ADP-G-actin and caps filament barbed ends: implications in motility |
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| Emmanuèle Helfer1, 3, Elisa M Nevalainen2, 3, Perttu Naumanen2, Stéphane Romero1, Dominique Didry1, Dominique Pantaloni1, Pekka Lappalainen2 and Marie-France Carlier1 |
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1 Cytoskeleton Dynamics and Motility, LEBS, CNRS, Gif-sur-Yvette, France 2 Institute of Biotechnology, University of Helsinki, Finland To whom correspondence should be addressed Marie-France Carlier, Dynamique du Cytosquelette, LEBS, CNRS, Gif-sur-Yvette F-91198, France. Tel.: +33 1 69 82 34 65; Fax: +33 1 69 82 341 29; E-mail: carlier@lebs.cnrs-gif.fr Pekka Lappalainen, Institute of Biotechnology, University of Helsinki, Finland. Tel.: +358 9 191 59499; E-mail: Pelappal@operoni.helsinki.fi 3 These authors equally contributed to the work Received 30 June 2005; Accepted 2 February 2006; Published online 2 March 2006. |
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| Abstract |
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| Twinfilins are conserved actin-binding proteins composed of two actin depolymerizing factor homology (ADF-H) domains. Twinfilins are involved in diverse morphological and motile processes, but their mechanism of action has not been elucidated. Here, we show that mammalian twinfilin both sequesters ADP-G-actin and caps filament barbed ends with preferential affinity for ADP-bound ends. Twinfilin replaces capping protein and promotes motility of N-WASP functionalized beads in a biomimetic motility assay, indicating that the capping activity supports twinfilin's function in motility. Consistently, in vivo twinfilin localizes to actin tails of propelling endosomes. The ADP-actin-sequestering activity cooperates with the filament capping activity of twinfilin to finely regulate motility due to processive filament assembly catalyzed by formin-functionalized beads. The isolated ADF-H domains do not cap barbed ends nor promote motility, but sequester ADP-actin, the C-terminal domain showing the highest affinity. A structural model for binding of twinfilin to barbed ends is proposed based on the similar foldings of twinfilin ADF-H domains and gelsolin segments. |
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| Keywords: actin, ADF homology domains, capping proteins, motility, twinfilin |
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Top of page MORE ARTICLES LIKE THISThese links to content published by NPG are automatically generated NEWS AND VIEWSCell motility Bare bones of the cytoskeleton Nature News and Views (07 Oct 1999) Nature Structural Biology News and Views (01 Sep 2001) RESEARCHJournal of Investigative Dermatology Letter Biological role and structural mechanism of twinfilin?capping protein interaction The EMBO Journal Article (04 Aug 2004) |
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