Identification of a phospholipase C-gamma1 (PLC-gamma1) SH3 domain-binding site in SLP-76 required for T-cell receptor-mediated activation of PLC-gamma1 and NFAT.
SLP-76 is an adapter protein required for T-cell receptor (TCR) signaling. In particular, TCR-induced tyrosine phosphorylation and activation of phospholipase C-gamma1 (PLC-gamma1), and the resultant TCR-inducible gene expression, depend on SLP-76. Nonetheless, the mechanisms by which SLP-76 mediates PLC-gamma1 activation are not well understood. We now demonstrate that SLP-76 directly ... interacts with the Src homology 3 (SH3) domain of PLC-gamma1. Structure-function analysis of SLP-76 revealed that each of the previously defined protein-protein interaction domains can be individually deleted without completely disrupting SLP-76 function. Additional deletion mutations revealed a new, 67-amino-acid functional domain within the proline-rich region of SLP-76, which we have termed the P-1 domain. The P-1 domain mediates a constitutive interaction of SLP-76 with the SH3 domain of PLC-gamma1 and is required for TCR-mediated activation of Erk, PLC-gamma1, and NFAT (nuclear factor of activated T cells). The adjacent Gads-binding domain of SLP-76, also within the proline-rich region, mediates inducible recruitment of SLP-76 to a PLC-gamma1-containing complex via the recruitment of both PLC-gamma1 and Gads to another cell-type-specific adapter, LAT. Thus, TCR-induced activation of PLC-gamma1 entails the binding of PLC-gamma1 to both LAT and SLP-76, a finding that may underlie the requirement for both LAT and SLP-76 to mediate the optimal activation of PLC-gamma1.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Binding Sites, Cell Fractionation, Cell Line, DNA-Binding Proteins, Enzyme Activation, Gene Expression Regulation, Genes, Reporter, Humans, Immunoblotting, Isoenzymes, Models, Biological, NFATC Transcription Factors, Nuclear Proteins, Phospholipase C gamma, Phosphoproteins, Phosphorylation, Protein Binding, Receptors, Antigen, T-Cell, Recombinant Fusion Proteins, Signal Transduction, Transcription Factors, Transfection, Type C Phospholipases, src Homology Domains
Adaptor Proteins, Signal Transducing, Binding Sites, Cell Fractionation, Cell Line, DNA-Binding Proteins, Enzyme Activation, Gene Expression Regulation, Genes, Reporter, Humans, Immunoblotting, Isoenzymes, Models, Biological, NFATC Transcription Factors, Nuclear Proteins, Phospholipase C gamma, Phosphoproteins, Phosphorylation, Protein Binding, Receptors, Antigen, T-Cell, Recombinant Fusion Proteins, Signal Transduction, Transcription Factors, Transfection, Type C Phospholipases, src Homology Domains
Mol. Cell. Biol.
Date: Jul. 01, 2001
PubMed ID: 11390650
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