The N-terminal SH2 Domains of Syk and ZAP-70 Mediate Phosphotyrosine-independent Binding to Integrin β Cytoplasmic Domains

Abstract

Syk and ZAP-70 form a subfamily of nonreceptor tyrosine kinases that contain tandem SH2 domains at their N termini. Engagement of these SH2 domains by tyrosine-phosphorylated immunoreceptor tyrosine-based activation motifs leads to kinase activation and downstream signaling. These kinases are also regulated by β3 integrin-dependent cell adhesion via a phosphorylation-independent interaction with the β3 integrin cytoplasmic domain. Here, we report that the interaction of integrins with Syk and ZAP-70 depends on the N-terminal SH2 domain and the interdomain A region of the kinase. The N-terminal SH2 domain alone is sufficient for weak binding, and this interaction is independent of tyrosine phosphorylation of the integrin tail. Indeed, phosphorylation of tyrosines within the two conserved NXXY motifs in the integrin β3 cytoplasmic domain blocks Syk binding. The tandem SH2 domains of these kinases bind to multiple integrin β cytoplasmic domains with varying affinities (β3 (K d = 24 nm) > β2 (K d = 38 nm) > β1 (K d = 71 nm)) as judged by both affinity chromatography and surface plasmon resonance. Thus, the binding of Syk and ZAP-70 to integrin β cytoplasmic domains represents a novel phosphotyrosine-independent interaction mediated by their N-terminal SH2 domains. Syk and ZAP-70 form a subfamily of nonreceptor tyrosine kinases that contain tandem SH2 domains at their N termini. Engagement of these SH2 domains by tyrosine-phosphorylated immunoreceptor tyrosine-based activation motifs leads to kinase activation and downstream signaling. These kinases are also regulated by β3 integrin-dependent cell adhesion via a phosphorylation-independent interaction with the β3 integrin cytoplasmic domain. Here, we report that the interaction of integrins with Syk and ZAP-70 depends on the N-terminal SH2 domain and the interdomain A region of the kinase. The N-terminal SH2 domain alone is sufficient for weak binding, and this interaction is independent of tyrosine phosphorylation of the integrin tail. Indeed, phosphorylation of tyrosines within the two conserved NXXY motifs in the integrin β3 cytoplasmic domain blocks Syk binding. The tandem SH2 domains of these kinases bind to multiple integrin β cytoplasmic domains with varying affinities (β3 (K d = 24 nm) > β2 (K d = 38 nm) > β1 (K d = 71 nm)) as judged by both affinity chromatography and surface plasmon resonance. Thus, the binding of Syk and ZAP-70 to integrin β cytoplasmic domains represents a novel phosphotyrosine-independent interaction mediated by their N-terminal SH2 domains. immunoreceptor tyrosine-based activation motif Chinese hamster ovary monoclonal antibody glutathione S-transferase 1,4-piperazinediethanesulfonic acid signaling lymphocyte-activation molecule SLAM-associated protein Integrin adhesion receptors bind components of the extracellular matrix or cell surface molecules and transmit signals that regulate processes such as cell proliferation, differentiation, migration, and death (reviewed in Refs. 1Hynes R.O. Cell. 1992; 69: 11-25Abstract Full Text PDF PubMed Scopus (8941) Google Scholar and 2Schwartz M.A. Schaller M.D. Ginsberg M.H. Annu. Rev. Cell Dev. Biol. 1995; 11: 549-599Crossref PubMed Scopus (1456) Google Scholar). Integrin signaling is initiated by ligand binding, which is thought to involve conformational changes in integrins that are propagated to their intracellular, cytoplasmic domains. The ability of integrins to function as signaling receptors is dependent on these cytoplasmic domains, which are typically short (13–70 amino acid residues in length) and lack known catalytic activity. Thus, integrins rely on either direct or indirect associations of their cytoplasmic domains with signaling and/or adaptor molecules to initiate signal transduction cascades. An early event in integrin signaling in certain cells involves activation of the nonreceptor tyrosine kinase Syk (3Clark E.A. Shattil S.J. Ginsberg M.H. Bolen J. Brugge J.S. J. Biol. Chem. 1994; 269: 28859-28864Abstract Full Text PDF PubMed Google Scholar, 4Lin T.H. Rosales C. Mondal K. Bolen J.B. Haskill S. Juliano R.L. J. Biol. Chem. 1995; 270: 16189-16197Abstract Full Text Full Text PDF PubMed Scopus (211) Google Scholar). In platelets, integrin αIIbβ3 engagement (3Clark E.A. Shattil S.J. Ginsberg M.H. Bolen J. Brugge J.S. J. Biol. Chem. 1994; 269: 28859-28864Abstract Full Text PDF PubMed Google Scholar) or clustering (5Gao J. Zoller K.E. Ginsberg M.H. Brugge J.S. Shattil S.J. EMBO J. 1997; 16: 6414-6425Crossref PubMed Scopus (160) Google Scholar) rapidly activates Syk in a manner independent of an intact actin cytoskeleton (4Lin T.H. Rosales C. Mondal K. Bolen J.B. Haskill S. Juliano R.L. J. Biol. Chem. 1995; 270: 16189-16197Abstract Full Text Full Text PDF PubMed Scopus (211) Google Scholar, 6Miranti C.K. Leng L. Maschberger P. Brugge J.S. Shattil S.J. Curr. Biol. 1998; 8: 1289-1299Abstract Full Text Full Text PDF PubMed Scopus (173) Google Scholar), differentiating integrin activation of Syk from that of another tyrosine kinase, FAK. Integrin αIIbβ3-dependent regulation of Syk depends on the direct interaction of Syk with the β3cytoplasmic domain (7Woodside D.G. Obergfell A. Leng L. Wilsbacher J.L. Miranti C.K. Brugge J.S. Shattil S.J. Ginsberg M.H. Curr. Biol. 2001; 11: 1799-1804Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar). Integrins of other classes including the β1 (4Lin T.H. Rosales C. Mondal K. Bolen J.B. Haskill S. Juliano R.L. J. Biol. Chem. 1995; 270: 16189-16197Abstract Full Text Full Text PDF PubMed Scopus (211) Google Scholar) and β2 (8Yan S.R. Huang M. Berton G. J. Immunol. 1997; 158: 1902-1910PubMed Google Scholar) integrins regulate Syk activity. Syk is essential for integrin β2-dependent morphological changes and respiratory burst in neutrophils (9Fernandez R. Suchard S.J. J. Immunol. 1998; 160: 5154-5162PubMed Google Scholar, 10Mocsai A. Zhou M. Meng F. Tybulewicz V.L. Lowell C.A. Immunity. 2002; 16: 547-558Abstract Full Text Full Text PDF PubMed Scopus (336) Google Scholar). However, the spectrum of integrin β cytoplasmic domains that bind Syk has yet to be assessed. The Syk family of kinases (Syk and Zap-70) are essential for normal development and function of the immune system (reviewed in Refs. 11Chu D.H. Morita C.T. Weiss A. Immunol. Rev. 1998; 165: 167-180Crossref PubMed Scopus (205) Google Scholar and12Turner M. Gulbranson-Judge A. Quinn M.E. Walters A.E. MacLennan I.C. Tybulewicz V.L. J. Exp. Med. 1997; 186: 2013-2021Crossref PubMed Scopus (143) Google Scholar), and Syk is required for the maintenance of vascular integrity (13Turner M. Mee P.J. Costello P.S. Williams O. Price A.A. Duddy L.P. Furlong M.T. Geahlen R.L. Tybulewicz V.L. Nature. 1995; 378: 298-302Crossref PubMed Scopus (643) Google Scholar,14Cheng A.M. Rowley B. Pao W. Hayday A. Bolen J.B. Pawson T. Nature. 1995; 378: 303-306Crossref PubMed Scopus (546) Google Scholar). These kinases are structurally distinct in that they contain tandem N-terminal SH2 domains followed by a C-terminal kinase domain. A helical Y-shaped linker region termed “interdomain A” joins the tandem SH2 domains. Kinase activity and subcellular localization of this kinase family within immune cells can be controlled by binding of its tandem SH2 domains to a doubly phosphorylated tyrosine ligand in immune response receptors (immunoreceptor tyrosine-based activation motif (ITAM))1 (11Chu D.H. Morita C.T. Weiss A. Immunol. Rev. 1998; 165: 167-180Crossref PubMed Scopus (205) Google Scholar). Linking the tandem SH2 domains with the kinase domain is the “interdomain B” region. This region contains a number of tyrosines that are phosphorylated in vivo and can recruit other signaling/adaptor molecules such as Src family members (15Pelosi M., Di, B., V Mounier V. Mege D. Pascussi J.M. Dufour E. Blondel A. Acuto O. J. Biol. Chem. 1999; 274: 14229-14237Abstract Full Text Full Text PDF PubMed Scopus (102) Google Scholar), Vav-1 (16Deckert M. Tartare-Deckert S. Couture C. Mustelin T. Altman A. Immunity. 1996; 5: 591-604Abstract Full Text PDF PubMed Scopus (244) Google Scholar), and Cbl (17Meng W. Sawasdikosol S. Burakoff S.J. Eck M.J. Nature. 1999; 398: 84-90Crossref PubMed Scopus (245) Google Scholar). Residues 6–370 in Syk and 1–337 in Zap-70, which contain the tandem SH2 domains and part of the interdomain B region, directly bind the integrin β3 cytoplasmic domain (7Woodside D.G. Obergfell A. Leng L. Wilsbacher J.L. Miranti C.K. Brugge J.S. Shattil S.J. Ginsberg M.H. Curr. Biol. 2001; 11: 1799-1804Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar). Furthermore, Syk(1–330) acts as a dominant interfering mutant with respect to integrin αIIbβ3-dependent regulation of Syk (7Woodside D.G. Obergfell A. Leng L. Wilsbacher J.L. Miranti C.K. Brugge J.S. Shattil S.J. Ginsberg M.H. Curr. Biol. 2001; 11: 1799-1804Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar). Integrin β3 cytoplasmic domain phosphorylation leads to binding of the adapter, Shc (18Cowan K.J. Law D.A. Phillips D.R. J. Biol. Chem. 2000; 275: 36423-36429Abstract Full Text Full Text PDF PubMed Scopus (83) Google Scholar). However, the interaction between Syk and integrin β3 tails does not require tyrosine phosphorylation of the β3 or intact in the Syk tandem SH2 domains (7Woodside D.G. Obergfell A. Leng L. Wilsbacher J.L. Miranti C.K. Brugge J.S. Shattil S.J. Ginsberg M.H. Curr. Biol. 2001; 11: 1799-1804Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar). report that Syk and ZAP-70 can directly with integrin and β3 cytoplasmic domains with Furthermore, the interaction involves the N-terminal SH2 domain of both kinases and is by the of the interdomain A region. Thus, the integrin interaction is mediated by a phosphorylation-independent interaction of an SH2 domain. The cell integrin F. C. Shattil S.J. Ginsberg M.H. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar) and in with and The cells at in antibody antibody number and for β3 integrin (7Woodside D.G. Obergfell A. Leng L. Wilsbacher J.L. Miranti C.K. Brugge J.S. Shattil S.J. Ginsberg M.H. Curr. Biol. 2001; 11: 1799-1804Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar). and from and from and L. J. J.L. Zoller M.J. Bolen J.B. Brugge J.S. Cell. Biol. 1995; PubMed Google Scholar). by a at of Syk by of and the by a at in both with the with and to the N-terminal SH2 domain of to the and amino acid residues of with and and with the and amino of and by and by of and cells with Syk or Syk with residues on or as A. M.A. M.A. Shattil S.J. J. Biol. Chem. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar). a at and the cells in and a at for of with antibody antibody at with protein A and for at in the immune by to and for the as L. J. J.L. Zoller M.J. Bolen J.B. Brugge J.S. Cell. Biol. 1995; PubMed Google Scholar). with for at The cells in with and and at The at for and with in The at and in in of Syk binding to integrin cytoplasmic domains, from by at protein of integrin cytoplasmic domains and β3 M. S. Ginsberg M.H. J. Biol. Chem. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). The β2 integrin cytoplasmic domain protein by of β2 and This a the N-terminal region of the β2 cytoplasmic in the The a downstream of The as in the system and and the M. S. Ginsberg M.H. J. Biol. Chem. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar) the of the by and by as M. S. Ginsberg M.H. J. Biol. Chem. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). The in of and of and the for at in the and in of with and to of A with and of with integrin cytoplasmic domain to the The for at with The in A with and The by in by and the with for direct binding The at a of and at a of Syk as The of integrin cytoplasmic protein in the direct binding is for of the cytoplasmic domain The integrin cytoplasmic domain and as B. D.A. B. Ginsberg M.H. J. Biol. Chem. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar). The N of Syk tyrosine kinase with integrin αIIbβ3 by binding to the β3cytoplasmic domain (7Woodside D.G. Obergfell A. Leng L. Wilsbacher J.L. Miranti C.K. Brugge J.S. Shattil S.J. Ginsberg M.H. Curr. Biol. 2001; 11: 1799-1804Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar). contains two N-terminal tandem SH2 domains by a linker termed interdomain A. the tandem SH2 domains is another linker region termed interdomain which contains a number of tyrosine residues that are vivo and regulate Syk and function (reviewed in 11Chu D.H. Morita C.T. Weiss A. Immunol. Rev. 1998; 165: 167-180Crossref PubMed Scopus (205) Google Scholar). The of Syk contains its kinase domain the integrin binding within we a number of Syk in A. In direct binding the interdomain B and C-terminal SH2 domain of Syk for binding In the N-terminal SH2 domain alone sufficient for interaction with the β3 the N-terminal SH2 domain for the interaction of with This binding to the β3 Thus, the N-terminal SH2 domain of Syk is sufficient for interaction with the integrin β3 cytoplasmic and is for of the N-terminal SH2 domain from its direct binding to the integrin β3 tail. of and for binding to integrin β3 or cytoplasmic domain protein by in by and by with of the is in the the of is of the of Syk to the integrin β3 cytoplasmic domain in A with Syk with integrin αIIbβ3 (7Woodside D.G. Obergfell A. Leng L. Wilsbacher J.L. Miranti C.K. Brugge J.S. Shattil S.J. Ginsberg M.H. Curr. Biol. 2001; 11: 1799-1804Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar) adhesion of cells to of the N-terminal SH2 domain integrin with Syk in cells integrin αIIbβ3 with Syk or Syk the N-terminal SH2 domain these cells on between αIIbβ3 and In Syk with αIIbβ3 The Syk at and of the The N-terminal SH2 domain is for binding to the integrin β3 and for the of Syk with integrin is a of Syk that directly to integrin β cytoplasmic domains (reviewed in 11Chu D.H. Morita C.T. Weiss A. Immunol. Rev. 1998; 165: 167-180Crossref PubMed Scopus (205) Google Scholar). a domain with Syk in and is essential for cell development and function M.E. M. Weiss A. 1994; PubMed Scopus Google Scholar, M.E. D. J. Weiss A. 1994; PubMed Scopus Google Scholar). the N-terminal SH2 domain of with the β3 integrin we the binding of to the β3 cytoplasmic domain. The N-terminal SH2 domain of directly the integrin β3 of the C-terminal SH2 domain of not Thus, in both ZAP-70 and binding to the integrin β3 cytoplasmic domain involves the N-terminal SH2 domain. In direct binding the interaction between Syk and N-terminal SH2 domains to be of affinity the tandem SH2 domains not and of the N-terminal SH2 domain of Syk does not binding of Syk to the integrin β3 cytoplasmic domain These that in to the N-terminal SH2 domains of Syk and be in binding to the integrin β3 tail. the C-terminal SH2 domain of Syk and to bind the integrin β3 cytoplasmic we the interdomain A region the interdomain A of Syk as a protein to directly with the cytoplasmic domain of binding The of the SH2 domains of Syk and are such that the domains bind to phosphorylated in a K. J. G. J. Biol. 1998; PubMed Scopus Google Scholar, J. M. Phillips K. Zoller M.J. J.L. Nature. 1995; PubMed Scopus Google Scholar). The tandem SH2 domains of are from of Syk and The in binding are and in P. S. S. Eck M.J. Cell. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). in a direct binding the tandem SH2 domains of not bind the β3 tails Thus, interaction with the integrin β3 cytoplasmic is not a of tandem SH2 the Syk interdomain A the interdomain region of to the integrin β3 cytoplasmic domain the of the interdomain A region of Zap-70, a of for binding to the integrin β3cytoplasmic domain. The N-terminal SH2 domain of Zap-70, in with its intact domain β3 to a as the tandem SH2 domains However, of the C-terminal of interdomain A in a in binding to of the N-terminal SH2 domain alone Thus, the interdomain A is for binding of Syk and to the cytoplasmic domain and binding to the tandem SH2 domains. The binding of Syk to the N-terminal SH2 domain and does not require phosphorylation of the two tyrosines in the β3 (7Woodside D.G. Obergfell A. Leng L. Wilsbacher J.L. Miranti C.K. Brugge J.S. Shattil S.J. Ginsberg M.H. Curr. Biol. 2001; 11: 1799-1804Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar). However, of these two tyrosine residues to within the β3 cytoplasmic domain can αIIbβ3-dependent D.A. P. K. Phillips D.R. Nature. 1999; PubMed Scopus Google Scholar). the of the on Syk or binding to the β3 tail. The on the binding of Syk or to the β3cytoplasmic domain of the β3 integrin cytoplasmic domain as a of integrin engagement D.A. L. Phillips D.R. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). phosphorylation of the β3 cytoplasmic domain Syk binding, tyrosine-phosphorylated or in the of the amino of the β3 cytoplasmic domain. at a and Syk at a of The for integrin β3 binding to Syk In a in Syk binding to the β3 in the of as with the phosphorylated The phosphorylated not this is in binding Shc (18Cowan K.J. Law D.A. Phillips D.R. J. Biol. Chem. 2000; 275: 36423-36429Abstract Full Text Full Text PDF PubMed Scopus (83) Google Scholar). Thus, of residues at β3 and does not Syk binding, the lack of for Furthermore, phosphorylation of its to for Syk binding to the β3 tail. Syk to the β3 integrin cytoplasmic domain. Syk activation engagement of integrins that contain other β (4Lin T.H. Rosales C. Mondal K. Bolen J.B. Haskill S. Juliano R.L. J. Biol. Chem. 1995; 270: 16189-16197Abstract Full Text Full Text PDF PubMed Scopus (211) Google Scholar, S.R. Huang M. Berton G. J. Immunol. 1997; 158: 1902-1910PubMed Google Scholar, R. Suchard S.J. J. Immunol. 1998; 160: 5154-5162PubMed Google Scholar, E. J. Cell Biol. 1998; PubMed Scopus Google Scholar, Geahlen R.L. J. Immunol. 1999; PubMed Scopus Google Scholar), we the interaction of Syk with other integrin β cytoplasmic tails The integrin β2 cytoplasmic domain Syk to the as to to binding of to of the cytoplasmic domain to Syk binding to β2 as Syk as and as The integrin cytoplasmic domains in the binding of not and a not of the integrin β cytoplasmic domains. Thus, Syk binding by the affinity of the interaction of the the affinity of Syk for integrin β tails is β3 > β2 > the affinity of the interaction between integrin cytoplasmic domains and binding by surface plasmon resonance. by to the and in This the ability to bind the integrin β3 cytoplasmic domain Integrin and β3 cytoplasmic domain and B. D.A. B. Ginsberg M.H. J. Biol. Chem. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar) at The at and the binding for Syk interaction with integrin cytoplasmic domains as B. D.A. B. Ginsberg M.H. J. Biol. Chem. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar). The are in In the cytoplasmic domain of β3 Syk with affinity (K 24 the integrin β3 cytoplasmic domain with not The binding of Syk to the integrin β2 cytoplasmic domain of affinity (K d = 38 the binding of the cytoplasmic domain to Syk of the affinity (K d = 71 plasmon of the binding between Syk and the integrin and β3cytoplasmic in a Syk and ZAP-70 form a subfamily of nonreceptor tyrosine kinases that contain tandem SH2 domains at their N The binding of Syk to the β3 integrin leads to its with integrin αIIbβ3 and to Syk activation (7Woodside D.G. Obergfell A. Leng L. Wilsbacher J.L. Miranti C.K. Brugge J.S. Shattil S.J. Ginsberg M.H. Curr. Biol. 2001; 11: 1799-1804Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar). Here, we report that the interaction of integrins with these kinases depends on the N-terminal SH2 domain and the interdomain A region of the kinase. The N-terminal SH2 domain alone is sufficient for weak binding, and this interaction is independent of tyrosine phosphorylation of the integrin tail. Indeed, phosphorylation of tyrosines within the two conserved NXXY motifs in the integrin β3 cytoplasmic domain blocks Syk binding. The tandem SH2 domains of these kinases bind to multiple integrin β cytoplasmic domains with varying affinities d = 24 nm) > d = 38 nm) > d = 71 nm)) as judged by both affinity chromatography and surface plasmon resonance. Thus, the binding of Syk and ZAP-70 to integrin β cytoplasmic domains represents a novel phosphotyrosine-independent interaction mediated by their N-terminal SH2 domains. The of the Syk N-terminal SH2 domain for its binding to integrin β cytoplasmic domains is on the N-terminal SH2 domain of Syk and Zap-70, not their C-terminal SH2 domains, are sufficient for binding to integrin β cytoplasmic domains. of this SH2 domain binding to integrin cytoplasmic domains in of the N-terminal SH2 domain of Syk of Syk with integrin αIIbβ3 in In the tandem SH2 domains of Syk and in an with phosphorylated tyrosines of K. J. G. J. Biol. 1998; PubMed Scopus Google J. M. Phillips K. Zoller M.J. J.L. Nature. 1995; PubMed Scopus Google Scholar). the N-terminal SH2 domains of Syk and function to binding of the C-terminal SH2 domain to L. J. J.L. Zoller M.J. Bolen J.B. Brugge J.S. Cell. Biol. 1995; PubMed Google Scholar, R.L. S. J. Biol. Chem. Full Text PDF PubMed Google Scholar) and with respect to binding E.A. J. Biol. Chem. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar), this domain does not bind phosphorylated motifs in L. J. J.L. Zoller M.J. Bolen J.B. Brugge J.S. Cell. Biol. 1995; PubMed Google Scholar, R.L. S. J. Biol. Chem. Full Text PDF PubMed Google Scholar). Indeed, to the of the N-terminal SH2 domain of Syk or not Thus, phosphotyrosine-independent binding to integrin β cytoplasmic domains is a novel function of the N-terminal SH2 domains of Syk and The tandem SH2 domains of Syk and are by an interdomain A that is in binding integrin cytoplasmic domains. of the N-terminal SH2 Syk to the integrin β3cytoplasmic with Furthermore, binding of the N-terminal SH2 domains of Syk and to integrin cytoplasmic domains the tandem SH2 domains. These two the of another region of Syk in the A as the the of interdomain A to the N-terminal SH2 domain binding to the β3 integrin cytoplasmic domain. within the interdomain A region in binding. This region of a motif in to the N-terminal SH2 domain J. M. Phillips K. Zoller M.J. J.L. Nature. 1995; PubMed Scopus Google Scholar). the in Syk has a K. J. G. J. Biol. 1998; PubMed Scopus Google Scholar) and and amino acid Furthermore, the tandem SH2 domains of not with the integrin β3 cytoplasmic domain. the interdomain of the tandem SH2 domains with the Syk interdomain A region in binding to the integrin β cytoplasmic domain. Thus, in to the N-terminal SH2 the interdomain A region of Syk and is in their binding to integrin β cytoplasmic domains. The interaction of Syk family kinases with integrin cytoplasmic domains is an of phosphotyrosine-independent interaction of an SH2 domain. The Syk and tandem SH2 domains with the phosphorylated The β3 cytoplasmic domain contains two conserved NXXY motifs that are to in However, the integrin cytoplasmic domains Syk and ZAP-70 and as judged by SH2 domains can with the interaction between the cytoplasmic domain of the signaling lymphocyte-activation molecule and SLAM-associated protein also and can in the of tyrosine phosphorylation C. M. D. S. L. R. G. C. Nature. 1998; PubMed Scopus Google Scholar, F. J. K. M. J. C. Eck M.J. Cell. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar, G. D. Pawson T. Curr. Biol. 1999; Full Text Full Text PDF PubMed Google Scholar, C. M. J. D.R. F. C. Pawson T. EMBO J. 2002; PubMed Scopus Google Scholar), is of SH2 domain. with the C. M. J. D.R. F. C. Pawson T. EMBO J. 2002; PubMed Scopus Google Scholar), which is also in the and β3 integrin cytoplasmic domains. However, the interaction is to require an intact in C. M. D. S. L. R. G. C. Nature. 1998; PubMed Scopus Google Scholar). not require intact (5Gao J. Zoller K.E. Ginsberg M.H. Brugge J.S. Shattil S.J. EMBO J. 1997; 16: 6414-6425Crossref PubMed Scopus (160) Google Scholar, D.G. Obergfell A. Leng L. Wilsbacher J.L. Miranti C.K. Brugge J.S. Shattil S.J. Ginsberg M.H. Curr. Biol. 2001; 11: 1799-1804Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar), and Syk tandem SH2 domains can with the integrin β3 cytoplasmic domain in the of with the that the N-terminal SH2 domain of Syk can directly bind integrin cytoplasmic domains, these that the β cytoplasmic domains of integrins with Syk kinase SH2 domains with a novel The of this phosphorylation of the integrin β3 cytoplasmic domain its with In a the C-terminal amino acid residues the two conserved NXXY for the β3 cytoplasmic binding to residues and Integrin β NXXY motifs can phosphorylated in vivo D.A. L. Phillips D.R. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). of the two NXXY tyrosines with Syk binding and phosphorylation Syk from integrin β Syk activation integrin The domain contains residues in the NXXY that activation of Syk and mutant integrin by and D.A. P. K. Phillips D.R. Nature. 1999; PubMed Scopus Google Scholar). These to of binding of such as L. D. Ginsberg M.H. Law D.A. Phillips D.R. J. Biol. Chem. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar) or Shc (18Cowan K.J. Law D.A. Phillips D.R. J. Biol. Chem. 2000; 275: 36423-36429Abstract Full Text Full Text PDF PubMed Scopus (83) Google Scholar) to the β3 D.R. J. M. L. Curr. Cell Biol. 2001; PubMed Scopus Google Scholar). the that tyrosine phosphorylation of the β3 cytoplasmic domain function by of Syk with the β3 to signaling. Syk signaling is known to in cytoplasmic M. A. T. T. T. EMBO J. 1994; PubMed Scopus Google Scholar), which of T. K. Nature. PubMed Scopus Google Scholar) and P. J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar). of the signaling of these mutant and the of this with Syk an of this of The integrin and domains directly bind Syk with and this interaction is to for integrin T.H. Rosales C. Mondal K. Bolen J.B. Haskill S. Juliano R.L. J. Biol. Chem. 1995; 270: 16189-16197Abstract Full Text Full Text PDF PubMed Scopus (211) Google Scholar), β2 (8Yan S.R. Huang M. Berton G. J. Immunol. 1997; 158: 1902-1910PubMed Google Scholar), and β3 (3Clark E.A. Shattil S.J. Ginsberg M.H. Bolen J. Brugge J.S. J. Biol. Chem. 1994; 269: 28859-28864Abstract Full Text PDF PubMed Google Scholar) regulation of Syk by surface plasmon the affinity of the integrin β3 cytoplasmic domain for Syk 24 in to the affinity of Syk for the phosphorylated E.A. J. Biol. Chem. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). However, integrins are on cells of A. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar) and of the cell M. Weiss A. J. Immunol. Google Scholar) on their cell Syk with αIIbβ3 integrins in C.K. Leng L. Maschberger P. Brugge J.S. Shattil S.J. Curr. Biol. 1998; 8: 1289-1299Abstract Full Text Full Text PDF PubMed Scopus (173) Google Scholar). of this kinase family to to the are to at their A. M.D. Immunity. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). binding to Syk directly its L. Zoller M.J. Brugge J.S. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar). Thus, the interaction with integrin cytoplasmic domains to or the regulation of Syk and ZAP-70 by immune response the and from Brugge and the of the β3 by Phillips and and