The zeta chain is associated with a tyrosine kinase and upon T-cell antigen receptor stimulation associates with ZAP-70, a 70-kDa tyrosine phosphoprotein.
Stimulation of the T-cell antigen receptor (TCR) leads to tyrosine phosphorylation of a number of cellular proteins, including phospholipase C (PLC) gamma 1 and the TCR zeta chain. We describe here a 70-kDa tyrosine phosphoprotein (ZAP-70) that associates with zeta within 15 sec following TCR stimulation. The phosphorylation of ZAP-70 and its association with zeta is independent of the other TCR chains since stimulation of a functional CD8/zeta chimeric receptor in a TCR-negative T cell leads to coprecipitation of ZAP-70 with the chimeric protein. In a Jurkat cell expressing the TCR and the CD8/zeta chimeric protein, tyrosine phosphorylation and association of ZAP-70 occurs exclusively with the stimulated receptor complex. In addition, a tyrosine kinase that does not appear to be fyn associates with the cytoplasmic domain of zeta and phosphorylates zeta and ZAP-70 in vitro.
Chan
A C
AC
Division of Rheumatology, Howard Hughes Medical Institute, University of California, San Francisco 94143.
Irving
B A
BA
Fraser
J D
JD
Weiss
A
A
D000596:Amino Acids / Q000032:analysis; D016827:CD8 Antigens / Q000502:physiology; D002460:Cell Line; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins; D008970:Molecular Weight; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D014162:Transfection; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
D000596:Amino Acids; D016827:CD8 Antigens; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; C054979:antigen T cell receptor, zeta chain; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases