Abstract
The zeta polypeptide is part of the T cell antigen receptor (TCR). The zeta-chain contributes to efficient cell-surface expression of the TCR and accounts for part of its signal transduction capability. TCR recognition triggers a complex set of events that result in cellular activation. The protein tyrosine kinase (PTK) Lck phosphorylates the zeta-chain, which in turn associates with another PTK, ZAP70, and stimulates its phosphorylation activity. Here we report the expression of the intracellular part of the zeta-chain and its biochemical characterization. The recombinant protein does not dimerize by itself in solution. Circular-dichroic analysis reveals a random coil conformation. zeta, phosphorylated using recombinant Lck, associates with recombinant ZAP70 tandem-SH2 domains. All three T cell activation motifs in zeta bind ZAP70 tandem-SH2 domains in vitro, forming a 1:3 complex. This result extends the picture, derived from earlier studies, of a mechanism for signal amplification.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Binding Sites
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Chromatography, Gel
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Circular Dichroism
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Cloning, Molecular
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Cross-Linking Reagents / metabolism
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Electrophoresis, Polyacrylamide Gel
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Escherichia coli / genetics
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Gene Expression
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Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
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Membrane Proteins / chemistry
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Membrane Proteins / metabolism*
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Phosphorylation
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Protein Binding
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Protein-Tyrosine Kinases / chemistry
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Protein-Tyrosine Kinases / metabolism*
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Receptors, Antigen, T-Cell / chemistry
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Receptors, Antigen, T-Cell / metabolism*
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Recombinant Proteins / isolation & purification
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Recombinant Proteins / metabolism
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T-Lymphocytes / metabolism*
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ZAP-70 Protein-Tyrosine Kinase
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src Homology Domains*
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src-Family Kinases / metabolism
Substances
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Cross-Linking Reagents
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Membrane Proteins
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Receptors, Antigen, T-Cell
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Recombinant Proteins
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antigen T cell receptor, zeta chain
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Protein-Tyrosine Kinases
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Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
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ZAP-70 Protein-Tyrosine Kinase
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src-Family Kinases