Adaptor protein Lnk associates with Tyr568 in c-Kit
Autor: | Hubert Serve, Saskia Gueller, H. Phillip Koeffler, Liqin Liu, Verena Nowak, Sigal Gery |
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Rok vydání: | 2008 |
Předmět: |
Plasma protein binding
SH2 domain Biochemistry Receptor tyrosine kinase Cell Line src Homology Domains Humans Immunoprecipitation Phosphorylation Binding site Molecular Biology Adaptor Proteins Signal Transducing biology Intracellular Signaling Peptides and Proteins Proteins Signal transducing adaptor protein Cell Biology Protein Structure Tertiary Erythropoietin receptor Proto-Oncogene Proteins c-kit Mutation biology.protein Tyrosine Signal transduction Protein Binding Proto-oncogene tyrosine-protein kinase Src |
Zdroj: | Biochemical Journal. 415:241-245 |
ISSN: | 1470-8728 0264-6021 |
Popis: | The adaptor protein Lnk is expressed in haemopoietic cells and plays a critical role in haemopoiesis. Animal model studies demonstrated that Lnk acts as a broad inhibitor of signalling pathways in haemopoietic lineages. Lnk belongs to a family of proteins sharing several structural motifs, including an SH2 (Src homology 2) domain which binds phosphotyrosine residues in various signal-transducing proteins. The SH2 domain is essential for Lnk-mediated negative regulation of several cytokine receptors [e.g. Mpl, EpoR (erythropoietin receptor), c-Kit]. Therefore inhibition of the binding of Lnk to cytokine receptors might lead to enhanced downstream signalling of the receptor and thereby to improved haemopoiesis in response to exposure to cytokines (e.g. erythropoietin in anaemic patients). This hypothesis led us to define the exact binding site of Lnk to the stem cell factor receptor c-Kit. Pull-down experiments using GST (glutathione transferase)-fusion proteins of the different domains of c-Kit showed that Lnk almost exclusively binds to the phosphorylated juxtamembrane domain. Binding of Lnk to the juxtamembrane domain was abolished by point mutation of Tyr568 and was competed by peptides with a phosphotyrosine residue at position 568. Co-immunoprecipitation with full-length wild-type or Y568F mutant c-Kit and Lnk confirmed these results, thus showing the importance of this phosphorylated tyrosine residue. Lnk bound directly to c-Kit without requiring other interacting partners. The identification of the binding site of Lnk to c-Kit will be useful to discover inhibitory molecules that prevent the binding of these two proteins, thus making haemopoietic cells more sensitive to growth factors. |
Databáze: | OpenAIRE |
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