Phosphorylated T cell receptor zeta-chain and ZAP70 tandem SH2 domains form a 1:3 complex in vitro.
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.
Weissenhorn
W
W
Laboratory of Molecular Medicine, Howard Hughes Medical Institute, Children's Hospital, Boston, MA 02212, USA.
Eck
M J
MJ
Harrison
S C
SC
Wiley
D C
DC
D001665:Binding Sites; D002850:Chromatography, Gel; D002942:Circular Dichroism; D003001:Cloning, Molecular; D003432:Cross-Linking Reagents / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*; D051746:ZAP-70 Protein-Tyrosine Kinase; D018909:src Homology Domains; D019061:src-Family Kinases / Q000378:metabolism
D003432:Cross-Linking Reagents; D008565:Membrane Proteins; D011948:Receptors, Antigen, T-Cell; D011994:Recombinant Proteins; C054979:antigen T cell receptor, zeta chain; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051746:ZAP-70 Protein-Tyrosine Kinase; D019061:src-Family Kinases