The Experts below are selected from a list of 22215 Experts worldwide ranked by ideXlab platform
Sang Hoon Rhee - One of the best experts on this subject based on the ideXlab platform.
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Src family kinase tyrosine phosphorylates Toll-like receptor 4 to dissociate MyD88 and Mal/Tirap, suppressing LPS-induced inflammatory responses.
Biochemical Pharmacology, 2018Co-Authors: Jonathon Mitchell, Su Jin Kim, Alexandra Seelmann, Brendan Veit, Brooke Shepard, Sang Hoon RheeAbstract:Src family kinases (SFKs) are a family of protein tyrosine kinases containing nine members: Src, LYN, Fgr, Hck, Lck, Fyn, Blk, Yes, and Ylk. Although SFK activation is a major immediate signaling event in LPS/Toll-like receptor 4 (TLR4) signaling, its precise role has remained elusive due to various contradictory results obtained from a certain SFK member-deficient mice or cells. The observed inconsistencies may be due to the compensation or redundancy by other SFKs upon a SFK deficiency. The chemical rescuing approach was suggested to induce temporal and precise SFK activation in living cells, thereby limiting the chance of cellular adaption to a SFK-deficient condition. Using the rescuing approach, we demonstrate that restoring SFK activity not only induces tyrosine phosphorylation of TLR4, but also inhibits LPS-induced NFκB and JNK1/2 activation and consequently suppresses LPS-induced cytokine production. TLR4 normally recruits TIR domain-containing adaptors in response to LPS, however, temporally restored SFK activation disrupts the LPS-induced association of MyD88 and Mal/Tirap with TLR4. Additionally, using kinase-dead SFK-LYN (Y397/508F) and constitutively active SFK-LYN (Y508F), we found that the kinase-dead SFK inhibits TLR4 tyrosine phosphorylation with reduced binding affinity to TLR4, while the kinase-active SFK strongly binds to TLR4 and promotes TLR4 tyrosine phosphorylation, suggesting that SFK kinase activity is required for TLR4 tyrosine phosphorylation and TLR4-SFK interaction. Together, our results demonstrate that SFK activation induces TLR4 tyrosine phosphorylation, consequently dissociating MyD88 and Mal/Tirap from TLR4 and inhibiting LPS-induced inflammatory responses, suggesting a negative feedback loop regulated by SFK-induced tyrosine phosphorylation in TLR4.
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src family kinase tyrosine phosphorylates toll like receptor 4 to dissociate myd88 and mal tirap suppressing lps induced inflammatory responses
Biochemical Pharmacology, 2018Co-Authors: Jonathon Mitchell, Su Jin Kim, Alexandra Seelmann, Brendan Veit, Brooke Shepard, Sang Hoon RheeAbstract:Src family kinases (SFKs) are a family of protein tyrosine kinases containing nine members: Src, LYN, Fgr, Hck, Lck, Fyn, Blk, Yes, and Ylk. Although SFK activation is a major immediate signaling event in LPS/Toll-like receptor 4 (TLR4) signaling, its precise role has remained elusive due to various contradictory results obtained from a certain SFK member-deficient mice or cells. The observed inconsistencies may be due to the compensation or redundancy by other SFKs upon a SFK deficiency. The chemical rescuing approach was suggested to induce temporal and precise SFK activation in living cells, thereby limiting the chance of cellular adaption to a SFK-deficient condition. Using the rescuing approach, we demonstrate that restoring SFK activity not only induces tyrosine phosphorylation of TLR4, but also inhibits LPS-induced NFκB and JNK1/2 activation and consequently suppresses LPS-induced cytokine production. TLR4 normally recruits TIR domain-containing adaptors in response to LPS, however, temporally restored SFK activation disrupts the LPS-induced association of MyD88 and Mal/Tirap with TLR4. Additionally, using kinase-dead SFK-LYN (Y397/508F) and constitutively active SFK-LYN (Y508F), we found that the kinase-dead SFK inhibits TLR4 tyrosine phosphorylation with reduced binding affinity to TLR4, while the kinase-active SFK strongly binds to TLR4 and promotes TLR4 tyrosine phosphorylation, suggesting that SFK kinase activity is required for TLR4 tyrosine phosphorylation and TLR4-SFK interaction. Together, our results demonstrate that SFK activation induces TLR4 tyrosine phosphorylation, consequently dissociating MyD88 and Mal/Tirap from TLR4 and inhibiting LPS-induced inflammatory responses, suggesting a negative feedback loop regulated by SFK-induced tyrosine phosphorylation in TLR4.
Clifford A Lowell - One of the best experts on this subject based on the ideXlab platform.
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b cell specific loss of LYN kinase leads to autoimmunity
Journal of Immunology, 2014Co-Authors: Chrystelle Lamagna, Anthony L. Defranco, Clifford A LowellAbstract:The LYN tyrosine kinase regulates inhibitory signaling in B and myeloid cells: loss of LYN results in a lupus-like autoimmune disease with hyperactive B cells and myeloproliferation. We have characterized the relative contribution of LYN-regulated signaling pathways in B cells specifically to the development of autoimmunity by crossing the novel LYN(flox/flox) animals with mice carrying the Cre recombinase under the control of the Cd79a promoter, resulting in deletion of LYN in B cells. The specific deletion of LYN in B cells is sufficient for the development of immune complex-mediated glomerulonephritis. The B cell-specific LYN-deficient mice have no defects in early bone marrow B cell development but have reduced numbers of mature B cells with poor germinal centers, as well as increased numbers of plasma and B1a cells, similar to the LYN(-/-) animals. Within 8 mo of life, B cell-specific LYN mutant mice develop high titers of IgG anti-Smith Ag ribonucleoprotein and anti-dsDNA autoantibodies, which deposit in their kidneys, resulting in glomerulonephritis. B cell-specific LYN mutant mice also develop myeloproliferation, similar to the LYN(-/-) animals. The additional deletion of MyD88 in B cells, achieved by crossing LYN(flox/flox)Cd79a-cre mice with myd88(flox/flox) animals, reversed the autoimmune phenotype observed in B cell-specific LYN-deficient mice by blocking production of class-switched pathogenic IgG autoantibodies. Our results demonstrate that B cell-intrinsic LYN-dependent signaling pathways regulate B cell homeostasis and activation, which in concert with B cell-specific MyD88 signaling pathways can drive the development of autoimmune disease.
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B Cell–Specific Loss of LYN Kinase Leads to Autoimmunity
Journal of immunology (Baltimore Md. : 1950), 2013Co-Authors: Chrystelle Lamagna, Anthony L. Defranco, Clifford A LowellAbstract:The LYN tyrosine kinase regulates inhibitory signaling in B and myeloid cells: loss of LYN results in a lupus-like autoimmune disease with hyperactive B cells and myeloproliferation. We have characterized the relative contribution of LYN-regulated signaling pathways in B cells specifically to the development of autoimmunity by crossing the novel LYN(flox/flox) animals with mice carrying the Cre recombinase under the control of the Cd79a promoter, resulting in deletion of LYN in B cells. The specific deletion of LYN in B cells is sufficient for the development of immune complex-mediated glomerulonephritis. The B cell-specific LYN-deficient mice have no defects in early bone marrow B cell development but have reduced numbers of mature B cells with poor germinal centers, as well as increased numbers of plasma and B1a cells, similar to the LYN(-/-) animals. Within 8 mo of life, B cell-specific LYN mutant mice develop high titers of IgG anti-Smith Ag ribonucleoprotein and anti-dsDNA autoantibodies, which deposit in their kidneys, resulting in glomerulonephritis. B cell-specific LYN mutant mice also develop myeloproliferation, similar to the LYN(-/-) animals. The additional deletion of MyD88 in B cells, achieved by crossing LYN(flox/flox)Cd79a-cre mice with myd88(flox/flox) animals, reversed the autoimmune phenotype observed in B cell-specific LYN-deficient mice by blocking production of class-switched pathogenic IgG autoantibodies. Our results demonstrate that B cell-intrinsic LYN-dependent signaling pathways regulate B cell homeostasis and activation, which in concert with B cell-specific MyD88 signaling pathways can drive the development of autoimmune disease.
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src family tyrosine kinase LYN mediates vwf gpib ix induced platelet activation via the cgmp signaling pathway
Blood, 2008Co-Authors: Hong Yin, Michael C Berndt, Junling Liu, Clifford A LowellAbstract:The platelet receptor for von Willebrand factor (VWF), glycoprotein (GP) Ib-IX, mediates initial platelet adhesion and transmits signals leading to platelet activation. Src family tyrosine kinases (SFKs) play an important role in VWF-induced GPIb-IX signaling. However, the SFK-dependent downstream signaling pathway is unclear but is thought to involve thromboxane A2 (TXA2) synthesis. Here we show that, although platelets deficient in SFK members, LYN or Fyn, were defective in the TXA2-dependent second wave of platelet aggregation induced by botrocetin/VWF, only LYN-knockout platelets were also defective in stable platelet adhesion to VWF under shear stress that is independent of the TXA2 pathway. LYN-knockout platelets also spread poorly on VWF but spread normally on fibrinogen, indicating an important role for LYN in VWF-mediated GPIb signaling but not in integrin outside-in signaling. Importantly, LYN knockout abrogated VWF-induced cGMP elevation. Addition of low concentrations of 8-bromo-cGMP, however, corrected the defective stable adhesion of LYN-knockout platelets or PP2-treated platelets on VWF. These results demonstrate an important role for LYN in VWF/GPIb-IX–induced integrin activation mediated via the cGMP signaling pathway independently of TXA2 synthesis and also indicate that LYN is critically important in GPIb-IX–mediated activation of the cGMP pathway.
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The Src family kinase Hck regulates mast cell activation by suppressing an inhibitory Src family kinase LYN
Blood, 2007Co-Authors: Hong Hong, Clifford A Lowell, Jiro Kitaura, Wenbin Xiao, Vaclav Horejsi, Yuko Kawakami, Toshiaki KawakamiAbstract:IgE/antigen-dependent mast cell activation plays a central role in immediate hypersensitivity and other allergic reactions. The Src family tyrosine kinase (SFK) LYN is activated by the cross-linking of high-affinity IgE receptors (FcϵRI). Activated LYN phosphorylates the FcϵRI subunits, β and γ, leading to subsequent activation of various signaling pathways. LYN also plays a negative regulatory function by activating negative regulatory molecules. Another SFK, Fyn, also contributes to mast cell degranulation by inducing Gab2-dependent microtubule formation. Here we show that a third SFK, Hck, plays a critical role in mast cell activation. Degranulation and cytokine production are reduced in FcϵRI-stimulated hck−/− mast cells. The reduced degranulation can be accounted for by defects in Gab2 phosphorylation and microtubule formation. Importantly, LYN activity is elevated in hck−/− cells, leading to increased phosphorylation of several negative regulators. However, positive regulatory events, such as activation of Syk, Btk, JNK, p38, Akt, and NF-κB, are substantially reduced in hck−/− mast cells. Analysis of LYN−/−hck−/−, LYN−/−FcϵRIβ−/−, and hck−/−FcϵRIβ−/− cells shows that Hck exerts these functions via both LYN-dependent and LYN-independent mechanisms. Thus, this study has revealed a hierarchical regulation among SFK members to fine-tune mast cell activation.
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Increased Expression of Genes Linked to FcεRI Signaling and to Cytokine and Chemokine Production in LYN-Deficient Mast Cells
Journal of immunology (Baltimore Md. : 1950), 2005Co-Authors: Valerie Hernandez-hansen, Clifford A Lowell, Bridget S Wilson, Julie D. J. Bard, Christy A. Tarleton, Julie A. Wilder, Janet M. OliverAbstract:Cross-linking the high-affinity IgE receptor, FceRI, on mast cells activates signaling pathways leading to the release of preformed inflammatory mediators and the production of cytokines and chemokines associated with allergic disorders. Bone marrow-derived mast cells (BMMCs) from LYN-deficient (LYN−/−) mice are hyperresponsive to FceRI cross-linking with multivalent Ag. Previous studies linked the hyperresponsive phenotype in part to increased Fyn kinase activity and reduced SHIP phosphatase activity in the LYN−/− BMMCs in comparison with wild-type (WT) cells. In this study, we compared gene expression profiles between resting and Ag-activated WT and LYN−/− BMMCs to identify other factors that may contribute to the hyperresponsiveness of the LYN−/− cells. Among genes implicated in the positive regulation of FceRI signaling, mRNA for the tyrosine kinase, Fyn, and for several proteins contributing to calcium regulation are more up-regulated following Ag stimulation in LYN−/− BMMCs than in WT BMMCs. Conversely, mRNA for the low-affinity IgG receptor (FcγRIIB), implicated in negative regulation of FceRI-mediated signaling, is more down-regulated in Ag-stimulated LYN−/− BMMCs than in WT BMMCs. Genes coding for proinflammatory cytokines and chemokines (IL-4, IL-6, IL-13, CSF, CCL1, CCL3, CCL5, CCL7, CCL9, and MIP1β)are all more highly expressed in Ag-stimulated LYN−/− mast cells than in WT cells. These microarray data identify LYN as a negative regulator in Ag-stimulated BMMCs of the expression of genes linked to FceRI signaling and also to the response pathways that lead to allergy and asthma.
Jonathon Mitchell - One of the best experts on this subject based on the ideXlab platform.
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Src family kinase tyrosine phosphorylates Toll-like receptor 4 to dissociate MyD88 and Mal/Tirap, suppressing LPS-induced inflammatory responses.
Biochemical Pharmacology, 2018Co-Authors: Jonathon Mitchell, Su Jin Kim, Alexandra Seelmann, Brendan Veit, Brooke Shepard, Sang Hoon RheeAbstract:Src family kinases (SFKs) are a family of protein tyrosine kinases containing nine members: Src, LYN, Fgr, Hck, Lck, Fyn, Blk, Yes, and Ylk. Although SFK activation is a major immediate signaling event in LPS/Toll-like receptor 4 (TLR4) signaling, its precise role has remained elusive due to various contradictory results obtained from a certain SFK member-deficient mice or cells. The observed inconsistencies may be due to the compensation or redundancy by other SFKs upon a SFK deficiency. The chemical rescuing approach was suggested to induce temporal and precise SFK activation in living cells, thereby limiting the chance of cellular adaption to a SFK-deficient condition. Using the rescuing approach, we demonstrate that restoring SFK activity not only induces tyrosine phosphorylation of TLR4, but also inhibits LPS-induced NFκB and JNK1/2 activation and consequently suppresses LPS-induced cytokine production. TLR4 normally recruits TIR domain-containing adaptors in response to LPS, however, temporally restored SFK activation disrupts the LPS-induced association of MyD88 and Mal/Tirap with TLR4. Additionally, using kinase-dead SFK-LYN (Y397/508F) and constitutively active SFK-LYN (Y508F), we found that the kinase-dead SFK inhibits TLR4 tyrosine phosphorylation with reduced binding affinity to TLR4, while the kinase-active SFK strongly binds to TLR4 and promotes TLR4 tyrosine phosphorylation, suggesting that SFK kinase activity is required for TLR4 tyrosine phosphorylation and TLR4-SFK interaction. Together, our results demonstrate that SFK activation induces TLR4 tyrosine phosphorylation, consequently dissociating MyD88 and Mal/Tirap from TLR4 and inhibiting LPS-induced inflammatory responses, suggesting a negative feedback loop regulated by SFK-induced tyrosine phosphorylation in TLR4.
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src family kinase tyrosine phosphorylates toll like receptor 4 to dissociate myd88 and mal tirap suppressing lps induced inflammatory responses
Biochemical Pharmacology, 2018Co-Authors: Jonathon Mitchell, Su Jin Kim, Alexandra Seelmann, Brendan Veit, Brooke Shepard, Sang Hoon RheeAbstract:Src family kinases (SFKs) are a family of protein tyrosine kinases containing nine members: Src, LYN, Fgr, Hck, Lck, Fyn, Blk, Yes, and Ylk. Although SFK activation is a major immediate signaling event in LPS/Toll-like receptor 4 (TLR4) signaling, its precise role has remained elusive due to various contradictory results obtained from a certain SFK member-deficient mice or cells. The observed inconsistencies may be due to the compensation or redundancy by other SFKs upon a SFK deficiency. The chemical rescuing approach was suggested to induce temporal and precise SFK activation in living cells, thereby limiting the chance of cellular adaption to a SFK-deficient condition. Using the rescuing approach, we demonstrate that restoring SFK activity not only induces tyrosine phosphorylation of TLR4, but also inhibits LPS-induced NFκB and JNK1/2 activation and consequently suppresses LPS-induced cytokine production. TLR4 normally recruits TIR domain-containing adaptors in response to LPS, however, temporally restored SFK activation disrupts the LPS-induced association of MyD88 and Mal/Tirap with TLR4. Additionally, using kinase-dead SFK-LYN (Y397/508F) and constitutively active SFK-LYN (Y508F), we found that the kinase-dead SFK inhibits TLR4 tyrosine phosphorylation with reduced binding affinity to TLR4, while the kinase-active SFK strongly binds to TLR4 and promotes TLR4 tyrosine phosphorylation, suggesting that SFK kinase activity is required for TLR4 tyrosine phosphorylation and TLR4-SFK interaction. Together, our results demonstrate that SFK activation induces TLR4 tyrosine phosphorylation, consequently dissociating MyD88 and Mal/Tirap from TLR4 and inhibiting LPS-induced inflammatory responses, suggesting a negative feedback loop regulated by SFK-induced tyrosine phosphorylation in TLR4.
Shigenobu Nakamura - One of the best experts on this subject based on the ideXlab platform.
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activated fyn phosphorylates α synuclein at tyrosine residue 125
Biochemical and Biophysical Research Communications, 2001Co-Authors: Takeshi Nakamura, Hiroshi Yamashita, Tetsuya Takahashi, Shigenobu NakamuraAbstract:Abstract α-Synuclein is a presynaptic protein of unknown function that has been implicated in the pathogenesis of several neurodegenerative diseases, including Parkinson's and Alzheimer's diseases. To gain insight into the functions of α-synuclein, we sought protein kinases that phosphorylate α-synuclein in the central nervous system. In contrast to LYN, PYK2, FAK, MAPK/ERK1, SAPK/JNK, and Cdk5, only Fyn could phosphorylate α-synuclein. In addition, A30P and A53T mutations did not affect the phosphorylation of α-synuclein by Fyn. Mutation analysis revealed that activated Fyn phosphorylates specifically tyrosine residue 125 of α-synuclein. The distribution of α-synuclein and Fyn expression was similar in various parts of the brain and was colocalized in subcellular structures. Since Fyn regulates various signal transduction pathways in the central nervous system and plays an essential role in the neuronal cell differentiation, survival, and plasticity, results of this paper indicate that phosphorylation of α-synuclein might be involved in one of the Fyn-mediated signaling pathways in neuronal cells.
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Activated Fyn phosphorylates alpha-synuclein at tyrosine residue 125.
Biochemical and biophysical research communications, 2001Co-Authors: Takeshi Nakamura, Hiroshi Yamashita, Tetsuya Takahashi, Shigenobu NakamuraAbstract:alpha-Synuclein is a presynaptic protein of unknown function that has been implicated in the pathogenesis of several neurodegenerative diseases, including Parkinson's and Alzheimer's diseases. To gain insight into the functions of alpha-synuclein, we sought protein kinases that phosphorylate alpha-synuclein in the central nervous system. In contrast to LYN, PYK2, FAK, MAPK/ERK1, SAPK/JNK, and Cdk5, only Fyn could phosphorylate alpha-synuclein. In addition, A30P and A53T mutations did not affect the phosphorylation of alpha-synuclein by Fyn. Mutation analysis revealed that activated Fyn phosphorylates specifically tyrosine residue 125 of alpha-synuclein. The distribution of alpha-synuclein and Fyn expression was similar in various parts of the brain and was colocalized in subcellular structures. Since Fyn regulates various signal transduction pathways in the central nervous system and plays an essential role in the neuronal cell differentiation, survival, and plasticity, results of this paper indicate that phosphorylation of alpha-synuclein might be involved in one of the Fyn-mediated signaling pathways in neuronal cells.
Mark J Zoller - One of the best experts on this subject based on the ideXlab platform.
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Phage display selection of ligand residues important for Src homology 3 domain binding specificity
Proceedings of the National Academy of Sciences of the United States of America, 1995Co-Authors: R J Rickles, Xiao-mai Zhou, Pamela A. Henry, Martyn C Botfield, Joan S Brugge, Mark J ZollerAbstract:The Src homology 3 (SH3) domain is a 50-aa modular unit present in many cellular proteins involved in intracellular signal transduction. It functions to direct protein-protein interactions through the recognition of proline-rich motifs on associated proteins. SH3 domains are important regulatory elements that have been demonstrated to specify distinct regulatory pathways important for cell growth, migration, differentiation, and responses to the external milieu. By the use of synthetic peptides, ligands have been shown to consist of a minimum core sequence and to bind to SH3 domains in one of two pseudosymmetrical orientations, class I and class II. The class I sites have the consensus sequence ZP(L/P)PP psi P whereas the class II consensus is PP psi PPZ (where psi is a hydrophobic residue and Z is a SH3 domain-specific residue). We previously showed by M13 phage display that the Src, Fyn, LYN, and phosphatidylinositol 3-kinase (PI3K) SH3 domains preferred the same class I-type core binding sequence, RPLPP psi P. These results failed to explain the specificity for cellular proteins displayed by SH3 domains in cells. In the current study, class I and class II core ligand sequences were displayed on the surface of bacteriophage M13 with five random residues placed either N- or C-terminal of core ligand residues. These libraries were screened for binding to the Src, Fyn, LYN, Yes, and PI3K SH3 domains. By this approach, additional ligand residue preferences were identified that can increase the affinity of SH3 peptide ligands at least 20-fold compared with core peptides. The amino acids selected in the flanking sequences were similar for Src, Fyn, and Yes SH3 domains; however, LYN and PI3K SH3 domains showed distinct binding specificities. These results indicate that residues that flank the core binding sequences shared by many SH3 domains are important determinants of SH3 binding affinity and selectivity.
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identification of src fyn LYN pi3k and abl sh3 domain ligands using phage display libraries
The EMBO Journal, 1994Co-Authors: R J Rickles, Martyn C Botfield, Zhigang Weng, O M Green, J A Taylor, Joan S Brugge, Mark J ZollerAbstract:Abstract Many proteins involved in intracellular signal transduction contain a small, 50-60 amino acid domain, termed the Src homology 3 (SH3) domain. This domain appears to mediate critical protein-protein interactions that are involved in responses to extracellular signals. Previous studies have shown that the SH3 domains from several proteins recognize short, contiguous amino acid sequences that are rich in proline residues. While all SH3 recognition sequences identified to date share a conserved P-X-X-P motif, the sequence recognition specificity of individual SH3 domains is poorly understood. We have employed a novel modification of phage display involving biased libraries to identify peptide ligands of the Src, Fyn, LYN, PI3K and Abl SH3 domains. With biased libraries, we probed SH3 recognition over a 12 amino acid window. The Src SH3 domain prefers the sequence XXXRPLPPLPXP, Fyn prefers XXXRPLPP(I/L)PXX, LYN prefers RXXRPLPPLPXP, PI3K prefers RXXRPLPPLPP while the Abl SH3 domain selects phage containing the sequence PPPYPPPP(I/V)PXX. We have also analysed the binding properties of Abl and Src SH3 ligands. We find that although the phage-displayed Abl and Src SH3 ligands are proline rich, they are distinct. In surface plasmon resonance binding assays, these SH3 domains displayed highly selective binding to their cognate ligands when the sequences were displayed on the surface of the phage or as synthetic peptides. The selection of these high affinity SH3 peptide ligands provides valuable information on the recognition motifs of SH3 domains, serve as new tools to interfere with the cellular functions of SH3 domain-mediated processes and form the basis for the design of SH3-specific inhibitors of disease pathways.
