Scaffold Protein SLP-76 Primes PLCγ1 for Activation by ITK-Mediated Phosphorylation.
Activation of the phospholipase, PLCγ1, is critical for proper T cell signaling following antigen receptor engagement. In T cells, the Tec family kinase, interleukin-2-induced tyrosine kinase (ITK), phosphorylates PLCγ1 at tyrosine 783 (Y783) leading to activation of phospholipase function and subsequent production of the second messengers inositol 1,4,5-trisphosphate and diacylglycerol. In this work, we demonstrate that PLCγ1 can be primed for ITK-mediated phosphorylation on Y783 by a specific region of the adaptor protein, SLP-76. The SLP-76 phosphotyrosine-containing sequence, pY(173)IDR, does not conform to the canonical recognition motif for an SH2 domain yet binds with significant affinity to the C-terminal SH2 domain of PLCγ1 (SH2C). The SLP-76 pY(173) motif competes with the autoinhibited conformation surrounding the SH2C domain of PLCγ1 leading to exposure of the ITK recognition element on the PLCγ1 SH2 domain and release of the target tyrosine, Y783. These data contribute to the evolving model for the molecular events occurring early in the T cell activation process.
Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA.
Sujan
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Devkota
Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA.
Raji E
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Joseph
Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19711, USA.
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Min
Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA.
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Bruce Fulton
Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA. Electronic address: amyand@iastate.edu.
Amy H
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Andreotti
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D004789:Enzyme Activation; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D051966:Phospholipase C gamma / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D018909:src Homology Domains / Q000235:genetics* / Q000276:immunology
D048868:Adaptor Proteins, Signal Transducing; D010750:Phosphoproteins; C092947:SLP-76 signal Transducing adaptor proteins; D015544:Inositol 1,4,5-Trisphosphate; D011505:Protein-Tyrosine Kinases; C080813:emt protein-tyrosine kinase; D051966:Phospholipase C gamma
SH2 domain; T cell signaling; autoinhibitory; phosphotyrosine; substrate priming