Structural Basis of the Migfilin-Filamin Interaction and Competition with Integrin β Tails

Abstract

A link between sites of cell adhesion and the cytoskeleton is essential for regulation of cell shape, motility, and signaling. Migfilin is a recently identified adaptor protein that localizes at cell-cell and cell-extracellular matrix adhesion sites, where it is thought to provide a link to the cytoskeleton by interacting with the actin cross-linking protein filamin. Here we have used x-ray crystallography, NMR spectroscopy, and protein-protein interaction studies to investigate the molecular basis of migfilin binding to filamin. We report that the N-terminal portion of migfilin can bind all three human filamins (FLNa, -b, or -c) and that there are multiple migfilin-binding sites in FLNa. Human filamins are composed of an N-terminal actin-binding domain followed by 24 immunoglobulin-like (IgFLN) domains and we find that migfilin binds preferentially to IgFLNa21 and more weakly to IgFLNa19 and -22. The filamin-binding site in migfilin is localized between Pro5 and Pro19 and binds to the CD face of the IgFLNa21 β-sandwich. This interaction is similar to the previously characterized β7 integrin-IgFLNa21 interaction and migfilin and integrin β tails can compete with one another for binding to IgFLNa21. This suggests that competition between filamin ligands for common binding sites on IgFLN domains may provide a general means of modulating filamin interactions and signaling. In this specific case, displacement of integrin tails from filamin by migfilin may provide a mechanism for switching between different integrin-cytoskeleton linkages. A link between sites of cell adhesion and the cytoskeleton is essential for regulation of cell shape, motility, and signaling. Migfilin is a recently identified adaptor protein that localizes at cell-cell and cell-extracellular matrix adhesion sites, where it is thought to provide a link to the cytoskeleton by interacting with the actin cross-linking protein filamin. Here we have used x-ray crystallography, NMR spectroscopy, and protein-protein interaction studies to investigate the molecular basis of migfilin binding to filamin. We report that the N-terminal portion of migfilin can bind all three human filamins (FLNa, -b, or -c) and that there are multiple migfilin-binding sites in FLNa. Human filamins are composed of an N-terminal actin-binding domain followed by 24 immunoglobulin-like (IgFLN) domains and we find that migfilin binds preferentially to IgFLNa21 and more weakly to IgFLNa19 and -22. The filamin-binding site in migfilin is localized between Pro5 and Pro19 and binds to the CD face of the IgFLNa21 β-sandwich. This interaction is similar to the previously characterized β7 integrin-IgFLNa21 interaction and migfilin and integrin β tails can compete with one another for binding to IgFLNa21. This suggests that competition between filamin ligands for common binding sites on IgFLN domains may provide a general means of modulating filamin interactions and signaling. In this specific case, displacement of integrin tails from filamin by migfilin may provide a mechanism for switching between different integrin-cytoskeleton linkages. Functional connections between transmembrane adhesion receptors and the intracellular cytoskeleton permit transmission of biochemical signals and mechanical force across the plasma membrane and are essential to the development and functioning of multicellular animals (1.Evans E.A. Calderwood D.A. Science. 2007; 316: 1148-1153Crossref PubMed Scopus (405) Google Scholar). In many cases connections are formed at specialized sites involving assemblies of many adhesion molecules and cytoskeletal and signaling adaptors (2.Zaidel-Bar R. Itzkovitz S. Ma'ayan A. Iyengar R. Geiger B. Nat. Cell Biol. 2007; 9: 858-867Crossref PubMed Scopus (894) Google Scholar). Although many components of these adhesion complexes have now been identified, a complete understanding of how adhesion complexes function will require detailed information on individual components and how they interact or compete with other elements of this complex machinery. Here we characterize the interaction of a recently identified adaptor protein, migfilin, with the actin-binding protein filamin and examine how this influences interactions of filamin with integrin adhesion receptors. Migfilin, also termed filamin-binding LIM protein-1, is a LIM domain protein that localizes to both cell-extracellular matrix and cell-cell contact sites, where it is thought to provide a link between the actin cytoskeleton and integrin-extracellular matrix contact sites and cadherin-catenin cell-cell junctions, respectively (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google Scholar, 4.Takafuta T. Saeki M. Fujimoto T.T. Fujimura K. Shapiro S.S. J. Biol. Chem. 2003; 278: 12175-12181Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar, 5.Wu C. J. Cell Sci. 2005; 118: 659-664Crossref PubMed Scopus (62) Google Scholar). In this way, migfilin can modulate cell shape, migration, and cadherin-mediated cell-cell contacts. Increased migfilin expression is observed in human leiomyosarcoma and expression levels correlate with tumor grade although the molecular basis for this observation remains to be determined (6.Papachristou D.J. Gkretsi V. Tu Y. Shi X. Chen K. Larjava H. Rao U.N. Wu C. Histopathology. 2007; 51: 409-508Crossref Scopus (20) Google Scholar). Approximately 50 kDa in size, migfilin is composed of three C-terminal LIM domains, a central proline-rich region, and an N-terminal portion, which lacks any identifiable structural domains or sequence motifs. Alternative splicing can result in removal of the final LIM domain or the proline-rich region (5.Wu C. J. Cell Sci. 2005; 118: 659-664Crossref PubMed Scopus (62) Google Scholar). The LIM domains mediate binding to kindlin-2 (Mig-2) and are required for localization to focal adhesions (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google Scholar). The central proline-rich domain has recently been shown to bind to vasodilator-stimulated phosphoprotein, an interaction observed to be important for migfilin modulation of cell migration (7.Zhang Y. Tu Y. Gkretsi V. Wu C. J. Biol. Chem. 2006; 281: 12397-12407Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar). The N-terminal region binds to filamins (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google Scholar, 4.Takafuta T. Saeki M. Fujimoto T.T. Fujimura K. Shapiro S.S. J. Biol. Chem. 2003; 278: 12175-12181Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar) and this interaction is thought to provide a link to the actin cytoskeleton. Vertebrates have three homologous genes that encode filamin A, B, and C: of these, filamin A (FLNa) 6The abbreviations used are: FLNa, filamin A; ABD, actin-binding domain; GST, glutathione S-transferase. is the most abundant and widely expressed (8.Stossel T.P. Condeelis J. Cooley L. Hartwig J.H. Noegel A. Schleicher M. Shapiro S.S. Nat. Rev. Mol. Cell. Biol. 2001; 2: 138-145Crossref PubMed Scopus (834) Google Scholar, 9.van der Flier A. Sonnenberg A. Biochim. Biophys. Acta. 2001; 1538: 99-117Crossref PubMed Scopus (335) Google Scholar). These filamins are non-covalent dimers of two 280-kDa subunits composed of an N-terminal actin-binding domain (ABD) followed by 24 immunoglobulin-like domains (IgFLN1-24) with IgFLN24 mediating dimerization (10.Gorlin J.B. Yamin R. Egan S. Stewart M. Stossel T.P. Kwiatkowski D.J. Hartwig J.H. J. Cell Biol. 1990; 111: 1089-1105Crossref PubMed Scopus (434) Google Scholar, 11.Pudas R. Kiema T.R. Butler P.J. Stewart M. Ylanne J. Structure (Camb.). 2005; 13: 111-119Abstract Full Text Full Text PDF PubMed Scopus (85) Google Scholar). A flexible hinge region separates IgFLN1-15 (rod 1), which contains a secondary actin-binding site and IgFLN16-24 (rod 2) allowing filamin to stabilize high angle actin fiber cross-links (12.Nakamura F. Osborn T.M. Hartemink C.A. Hartwig J.H. Stossel T.P. J. Cell Biol. 2007; 179: 1011-1025Crossref PubMed Scopus (216) Google Scholar). In addition to their role as actin cross-linking proteins, filamins, mostly through their C-terminal domains, IgFLN16-24, bind an array of cytosolic signaling and adaptor proteins and transmembrane receptors (8.Stossel T.P. Condeelis J. Cooley L. Hartwig J.H. Noegel A. Schleicher M. Shapiro S.S. Nat. Rev. Mol. Cell. Biol. 2001; 2: 138-145Crossref PubMed Scopus (834) Google Scholar, 13.Feng Y. Walsh C.A. Nat. Cell Biol. 2004; 6: PubMed Scopus Google Scholar, Schleicher M. Noegel Sci. 2006; Full Text Full Text PDF PubMed Scopus Google that filamins complex and the We have previously identified IgFLNa21 as the binding site in for integrin adhesion receptors and the of IgFLNa21 in complex with a β7 integrin that IgFLNa21 a composed of two T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). The CD face of the IgFLNa21 is the interaction site for the β7 integrin and of other interactions that the CD face of IgFLN domains a common for binding T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). studies and from cell have migfilin binding to and (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google Scholar). This in the binding of for migfilin and tails the migfilin bind the CD face of in a to the interaction between IgFLNa21 and β7 integrin and 2) migfilin and compete for binding to the IgFLNa21 recently a migfilin with an N-terminal region to migfilin shown to interact with a secondary migfilin binding site filamins T. Saeki M. Fujimoto T.T. Fujimura K. Shapiro S.S. J. Biol. Chem. 2003; 278: 12175-12181Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar). biochemical and NMR we find that contains multiple migfilin-binding that the of migfilin is binding to in the CD face in a similar to from β7 and of proteins the molecular basis of The interaction between migfilin and IgFLNa21 is of with it is of of integrin tails by migfilin provide a mechanism for switching from one of to involving kindlin-2 in cell and integrin and and The has been previously T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). migfilin or by and or has been previously Y. Kiema T. Calderwood D.A. Ylanne J. J. 2007; PubMed Scopus Google and 2) by by A. Sonnenberg der Flier A. M. T. Shapiro S.S. Sonnenberg A. J. Cell Biol. PubMed Scopus Google Scholar). a from and F. M. der of and and IgFLNa21 and have been previously T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). with the and by with migfilin proteins as for integrin proteins and and as previously T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar, Y. Calderwood D.A. 2007; PubMed Scopus Google Scholar). migfilin to as previously Y. Calderwood D.A. 2007; PubMed Scopus Google proteins by and by or protein Migfilin and from the binding of of proteins to migfilin tails by as binding and to a one site binding for with the and 24 to and on of and with or as previously T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar, M. A. C. S. A. R. Mol. Biol. Cell. 2003; PubMed Scopus Google Scholar). IgFLNa21 and IgFLNa19 and the in T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar, Y. Kiema T. Calderwood D.A. Ylanne J. J. 2007; PubMed Scopus Google Scholar). The a and in and the the N-terminal and C-terminal from NMR in 50 and with at and The a in a R. T. PubMed Scopus Google the with a sequence J. M. M. C. J. PubMed Scopus Google Scholar) on a of migfilin and the protein the for by the NMR The NMR and F. S. J. A. J. 6: PubMed Scopus Google Scholar) and the binding site the of where and are the in the and respectively A. Y. Nat. Biol. 2001; PubMed Scopus Google Scholar). The an to the of the with R. M. K. J. Mol. PubMed Scopus Google Scholar). The binding a interaction to of with the in the and as 2) where for the observed at and are the protein and in by the of protein and the and and IgFLNa21 and as previously T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). at by an of IgFLNa21 and migfilin in with the of and in The at at the Structure and with for J. Scopus Google Scholar) and the by molecular with the Biol. 2004; PubMed Scopus Google Scholar) A as the and by A. R. Nat. Biol. 6: PubMed Scopus Google Biol. PubMed Scopus Google and K. Biol. 2004; PubMed Scopus Google Scholar). The migfilin by with between A and used in the The and of the have been as The and are in and of by The interaction with the of the in of of from in most of the in in a The N-terminal of Migfilin to A, B, and or have been as filamin-binding proteins (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google Scholar, 4.Takafuta T. Saeki M. Fujimoto T.T. Fujimura K. Shapiro S.S. J. Biol. Chem. 2003; 278: 12175-12181Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar) and the N-terminal portion of migfilin has been in filamin the of this interaction we two migfilin the complete an N-terminal and a the central region and the C-terminal LIM These expressed in as N-terminal proteins and on in we that binds from cell the C-terminal portion binding for and Migfilin in and of has been shown to bind sites in the region of and (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google the migfilin which contains the filamin-binding portion, to bind to T. Saeki M. Fujimoto T.T. Fujimura K. Shapiro S.S. J. Biol. Chem. 2003; 278: 12175-12181Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar). We the of migfilin to 1), which contains the actin-binding domains and (rod shown in the of migfilin both the C-terminal portion to interact with the N-terminal of migfilin mediate binding to all filamins and migfilin can bind filamin at sites in and Migfilin IgFLNa21 we have that migfilin binds to both and of in most proteins interact with sites in (8.Stossel T.P. Condeelis J. Cooley L. Hartwig J.H. Noegel A. Schleicher M. Shapiro S.S. Nat. Rev. Mol. Cell. Biol. 2001; 2: 138-145Crossref PubMed Scopus (834) Google Scholar, 13.Feng Y. Walsh C.A. Nat. Cell Biol. 2004; 6: PubMed Scopus Google Scholar, Schleicher M. Noegel Sci. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). We have also that the CD face of domains in this region as a general binding T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). We to characterize the interactions between migfilin and domains in Tu (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google Scholar) localized the migfilin binding site to in the of and the binding site in to domains We used binding with individual domains and to in a IgFLNa21 binds migfilin we also binding to IgFLNa19 and The interaction between and IgFLNa21 is as migfilin bind to or to A and The interaction with IgFLNa21 and with an of We previously characterized the interaction between integrin β domains and IgFLNa21 and identified in the and of the IgFLNa21 β that integrin binding T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). migfilin binds to a similar on and in and in in and binding to or on or migfilin binding This result is similar to that observed for that migfilin and β7 may bind to a similar site on IgFLNa21. The in the interaction between migfilin and filamin we to investigate the molecular of the of migfilin in The of has of an A. J. PubMed Scopus Google Scholar). complete for all the which that the protein is flexible D.A. A. PubMed Scopus Google Scholar). Migfilin to previously T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar, D.A. A. Nat. Cell Biol. 2001; PubMed Scopus Google Scholar) that two and in the β7 integrin important with IgFLNa21. We the sequence for filamin-binding sites a to the filamin-binding from β7 T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google H. M. T. M. Kiema T. Ylanne J. PubMed Scopus Google and Y. Kiema T. Calderwood D.A. Ylanne J. J. 2007; PubMed Scopus Google Scholar) with This to a that between Pro5 and Pro19 be the filamin-binding site with where of or the in migfilin filamin binding (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google Scholar). A migfilin a NMR binding observed with the of binding the with the of this interaction is to be in with the from examine the interaction of the with for NMR Although the to at the to in the and This suggests that is the filamin binding sequence in with migfilin an NMR with the and with at a that of migfilin are specific for IgFLNa21. Migfilin to the of IgFLNa21 in a to β the interaction of IgFLNa21 and migfilin at the we the migfilin with IgFLNa21. The to the and to The by molecular the of IgFLNa21 T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar) as the The molecular a with two IgFLNa21 molecules in the for of the migfilin between the two IgFLNa21 The to and In the final the two IgFLNa21 molecules to other for and to the previously IgFLNa21 for with The migfilin is to β of both IgFLNa21 molecules and the two β In this of the have interactions with both IgFLNa21 The by the is on A and on B. of the migfilin interactions observed are similar to between integrin and β7 domains and IgFLNa21 T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar, H. M. T. M. Kiema T. Ylanne J. PubMed Scopus Google Scholar) In addition to the the interactions between the and A by of and of and The interactions with IgFLNa21 by and investigate the of the interaction between migfilin and IgFLNa21 in the in of by the migfilin by NMR and on the of IgFLNa21 The in IgFLNa21 are on the CD face of IgFLNa21 and are similar to that observed for the of β7 to IgFLNa21 T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). with the from x-ray and that that of the or migfilin binding this migfilin binding to the CD face of IgFLN The the used for a migfilin can bind two IgFLNa21 In both the interaction is similar to previously characterized integrin-IgFLNa21 interactions T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar, H. M. T. M. Kiema T. Ylanne J. PubMed Scopus Google Scholar) and for the of in NMR This suggests that one of the two interactions in the may be investigate we the binding of a of migfilin The IgFLNa21 A interaction migfilin and interaction migfilin and we of these in the and binding to IgFLNa21 by in of or observed to or of the observed for a IgFLNa21 on addition of and migfilin is shown in the binding in this at migfilin In the two and to This suggests that the IgFLNa21 interaction the binding in the role of and for the interaction to and to and the of or migfilin to bind the and IgFLNa21 binding and are important for the binding of to with the interaction between A and the migfilin in Tu (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google Scholar) previously that a in interaction with filamin. These at the N-terminal of the filamin-binding is in is the migfilin in the We the of this on Although a binding of of to to any in binding a more that migfilin binding with and filamin domains that migfilin binds to the CD face of IgFLNa21 and IgFLNa19 in a similar to the β7 shown in migfilin also binds to sites in We or in migfilin, which binding to migfilin binding to FLNa. shown in these the of to from cell to bind or (rod 2) of This suggests that migfilin may interact with a of IgFLN domains a similar Migfilin with β for to that both migfilin and β bind to the CD face of IgFLNa21 T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). migfilin can compete with β for IgFLNa21 binding we the of of a on the binding of to of integrin β7 The migfilin a of IgFLNa21 binding to β7 integrin tails The with a migfilin in of migfilin binds to the CD face on IgFLNa21 in a similar to β integrin tails and it has a it can compete for filamin Migfilin to has been shown to to cell-extracellular matrix focal and to actin is that adhesion is through binding to fiber localization is filamin binding (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google Scholar). We the localization of migfilin in of in of with fiber also actin fiber localization with (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google to at focal adhesions In is localized actin with in this in is with filamin-binding migfilin to actin a similar to In these filamin localization remains at actin and is by the Cell shape, size, and in the with filamin binding is required for migfilin localization to actin in A link between sites of cell adhesion and the cytoskeleton is essential for regulation of cell shape, motility, and signaling. Migfilin, which localizes at both cell-cell and cell-extracellular matrix adhesion sites, is thought to provide one link to the actin cytoskeleton through interaction with the actin-binding and cross-linking protein filamin. Here we have the molecular basis of migfilin interactions with filamin and the of IgFLNa21 to a migfilin We find the N-terminal portion of migfilin, which is in all is in can bind to FLNa, -b, or 2) the filamin-binding site in migfilin is localized between and there are multiple migfilin-binding sites in migfilin binds preferentially to IgFLNa21 and more weakly to IgFLNa19 and migfilin binds to the CD face of IgFLNa21 and in the or this interaction as at or in migfilin and integrin β tails bind to a similar site on IgFLNa21 and can compete with one another for and the interaction is important for migfilin to in Migfilin previously been shown to bind sites in of and and of (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google Scholar, 4.Takafuta T. Saeki M. Fujimoto T.T. Fujimura K. Shapiro S.S. J. Biol. Chem. 2003; 278: 12175-12181Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar). We that migfilin can interact with all three filamins and binding to both and of FLNa. binding and to interacting domains we used proteins to that migfilin and the the binding observed with IgFLNa21. This suggests that one filamin may bind multiple migfilin The in of and the for the binding to remains to be multiple binding sites permit of to the actin cytoskeleton or provide allowing the actin to be in the of other filamin-binding structural has been T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar, H. M. T. M. Kiema T. Ylanne J. PubMed Scopus Google Scholar) and interactions F. R. Hartwig J.H. Stossel T.P. Ylanne J. 2006; PubMed Scopus Google dimerization R. Kiema T.R. Butler P.J. Stewart M. Ylanne J. Structure (Camb.). 2005; 13: 111-119Abstract Full Text Full Text PDF PubMed Scopus (85) Google and an interaction Y. Kiema T. Calderwood D.A. Ylanne J. J. 2007; PubMed Scopus Google Scholar). In all cases binding at the CD face of the IgFLN domain with the binding a β to which the of the IgFLN The provide for the that the CD face is a general binding on IgFLN T. Y. C. M. Ylanne J. Calderwood D.A. Mol. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). that migfilin bind the CD face of IgFLNa21 in a similar to integrin β of binding are observed in the A and bind one migfilin interaction are similar to previously characterized interactions NMR and that the interaction in is the one by A and The in this a the The sequence of the A is as shown in We that migfilin may both binding to two from the or different is that migfilin the for migfilin binding to filamins and that the CD face of IgFLNa19 and IgFLNa21 provide the Although it remains that other also to the interaction in in the or of the domain can migfilin binding as at or in or also the interaction of migfilin with filamins between all domain CD face are for in to that can the of other filamin-binding The of the CD face of IgFLN domains to bind filamin ligands suggests that competition may be a We this by the of the filamin-binding migfilin on integrin binding to IgFLNa21. the filamin-binding a filamin binding to integrin β between the many different filamin binding may provide a mechanism to filamin interactions and signaling. In the of this may provide a mechanism for switching between different to the actin interactions or complexes (3.Tu Y. Wu S. Shi X. Chen K. Wu C. Cell. 2003; 113: 37-47Abstract Full Text Full Text PDF PubMed Scopus (303) Google Scholar, T.P. Hartwig J.H. Cell. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, S. Calderwood D.A. D.A. J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, X. Tu Y. Chen K. Wu S. K. J. Wu C. J. Biol. Chem. 2007; Full Text Full Text PDF PubMed Scopus Google Scholar). that or migfilin binding to filamin suggests as another mechanism for is migfilin is in the sequence is with at that site by as in the or this site is a on the of we that migfilin binding to filamin. We that there is in this interaction as at the binding by NMR The binding of migfilin to all three filamins, the of migfilin-binding IgFLN domains in and observation that filamin that migfilin binding also binding of other filamin ligands it to investigate the of interactions filamin or and of migfilin in filamin binding that filamin binding is required for to actin in will be important to the of this interaction in migfilin animals or In we have used structural and biochemical to investigate the interaction between filamin and migfilin, a recently identified protein in regulation of cell motility, cell shape, and (5.Wu C. J. Cell Sci. 2005; 118: 659-664Crossref PubMed Scopus (62) Google Scholar). multiple binding sites in filamins and that migfilin a on IgFLN migfilin can compete with other filamin This has for understanding of the and of filamin signaling complexes and may provide a means for switching to the cytoskeleton. We the for of and for in and for with