Association of phosphatidylinositol 3-kinase with a specific sequence of the T cell receptor zeta chain is dependent on T cell activation.
The T cell antigen receptor (TCR).CD3 complex contains several distinct but related signal transduction modules termed "Reth motifs": one each in the cytoplasmic domains of CD3-gamma, -delta, and -epsilon chains and three in the CD3-zeta polypeptide (zeta A, zeta B, and zeta C). Cross-linking of individual motifs expressed in chimeric molecules leads to early and late T cell activation events. Although the activated T cell receptor associates with nonreceptor tyrosine kinases, the sites of interaction with kinases and other potential effector molecules have not been fully mapped. Here we show that phosphatidylinositol 3-kinase (PI 3-kinase) preferentially associated with the zeta chain membrane proximal motif zeta A. Maximal PI 3-kinase/zeta A association occurred following TCR.CD3 activation and was dependent upon phosphorylation of both tyrosine residues in zeta A. The association of PI 3-kinase was specific for zeta A and could be ranked zeta A >> zeta C > zeta B. Phosphorylation of the zeta A motif on tyrosine residues occurred in response to TCR.CD3 cross-linking in vivo. These results indicate that T cell activation leads to assembly of an intracellular signaling complex: recruitment of a tyrosine kinase, phosphorylation of zeta A, and association of PI 3-kinase. These data also support a model in which different Reth motifs of the TCR.CD3 complex recruit distinct signal transduction molecules. Thus, the subdomains of the T cell antigen receptor zeta chain may serve different roles during T cell maturation and antigen-driven activation.
Exley
M
M
Division of Immunology, Beth Israel Hospital, Harvard Medical School, Boston, Massachusetts 02215.
Varticovski
L
L
Peter
M
M
Sancho
J
J
Terhorst
C
C
D000595:Amino Acid Sequence; D000818:Animals; D017252:CD3 Complex / Q000378:metabolism; D002478:Cells, Cultured; D006801:Humans; D008213:Lymphocyte Activation; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011485:Protein Binding; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*
D017252:CD3 Complex; D008565:Membrane Proteins; D011948:Receptors, Antigen, T-Cell; C054979:antigen T cell receptor, zeta chain; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor)