CLEC-2 activates Syk through dimerization

Hughes, C. E. ORCID: https://orcid.org/0000-0002-9790-5820, Pollitt, A. Y. ORCID: https://orcid.org/0000-0001-8706-5154, Mori, J., Eble, J. A., Tomlinson, M. G., Hartwig, J. H., O'Callaghan, C. A., Fütterer, K. and Watson, S. P. (2010) CLEC-2 activates Syk through dimerization. Blood, 115 (14). pp. 2947-2955. ISSN 1528-0020 doi: 10.1182/blood-2009-08-237834

Abstract/Summary

The C-type lectin receptor CLEC-2 activates platelets through Src and Syk tyrosine kinases, leading to tyrosine phosphorylation of downstream adapter proteins and effector enzymes, including phospholipase-C gamma2. Signaling is initiated through phosphorylation of a single conserved tyrosine located in a YxxL sequence in the CLEC-2 cytosolic tail. The signaling pathway used by CLEC-2 shares many similarities with that used by receptors that have 1 or more copies of an immunoreceptor tyrosine-based activation motif, defined by the sequence Yxx(L/I)x(6-12)Yxx(L/I), in their cytosolic tails or associated receptor chains. Phosphorylation of the conserved immunoreceptor tyrosine-based activation motif tyrosines promotes Syk binding and activation through binding of the Syk tandem SH2 domains. In this report, we present evidence using peptide pull-down studies, surface plasmon resonance, quantitative Western blotting, tryptophan fluorescence measurements, and competition experiments that Syk activation by CLEC-2 is mediated by the cross-linking through the tandem SH2 domains with a stoichiometry of 2:1. In support of this model, cross-linking and electron microscopy demonstrate that CLEC-2 is present as a dimer in resting platelets and converted to larger complexes on activation. This is a unique mode of activation of Syk by a single YxxL-containing receptor.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/44577
Identification Number/DOI	10.1182/blood-2009-08-237834
Refereed	Yes
Divisions	Life Sciences > School of Biological Sciences > Biomedical Sciences
Publisher	American Society of Hematology
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