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Proc Natl Acad Sci U S A. 2009 Dec 15;106(50):21143-8. doi: 10.1073/pnas.0911309106. Epub 2009 Dec 1.

Itk tyrosine kinase substrate docking is mediated by a nonclassical SH2 domain surface of PLCgamma1.

Author information

1
Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA.

Abstract

Interleukin-2 tyrosine kinase (Itk) is a Tec family tyrosine kinase that mediates signaling processes after T cell receptor engagement. Activation of Itk requires recruitment to the membrane via its pleckstrin homology domain, phosphorylation of Itk by the Src kinase, Lck, and binding of Itk to the SLP-76/LAT adapter complex. After activation, Itk phosphorylates and activates phospholipase C-gamma1 (PLC-gamma1), leading to production of two second messengers, DAG and IP(3). We have previously shown that phosphorylation of PLC-gamma1 by Itk requires a direct, phosphotyrosine-independent interaction between the Src homology 2 (SH2) domain of PLC-gamma1 and the kinase domain of Itk. We now define this docking interface using a combination of mutagenesis and NMR spectroscopy and show that disruption of the Itk/PLCgamma1 docking interaction attenuates T cell signaling. The binding surface on PLCgamma1 that mediates recognition by Itk highlights a nonclassical binding activity of the well-studied SH2 domain providing further evidence that SH2 domains participate in important signaling interactions beyond recognition of phosphotyrosine.

PMID:
19955438
PMCID:
PMC2786894
DOI:
10.1073/pnas.0911309106
[Indexed for MEDLINE]
Free PMC Article

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