Association of the fyn protein-tyrosine kinase with the T-cell antigen receptor.
Activation of the T-cell antigen receptor (TCR) results in tyrosine phosphorylation of the TCR zeta chain and other intracellular substrates. Two other T-cell integral membrane proteins, CD4 and CD8, are associated with the protein-tyrosine kinase (PTK), lck. Despite evidence that activation of this enzyme results in TCR-zeta chain phosphorylation, it has not been shown that the TCR activates lck. We have sought evidence that the TCR is associated with a PTK. In this study we use digitonin to solubilize a murine T-cell hybridoma and demonstrate that antibodies binding extracellular but not intracellular domains of the TCR specifically coprecipitate only the fyn PTK and not lck or yes, two other kinases found in these cells. The association of the fyn PTK with the TCR might enable the T cell to independently regulate two PTKs through surface receptors.
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
L E
LE
Samelson
A F
AF
Phillips
E T
ET
Luong
R D
RD
Klausner
D000818:Animals; D015180:Electrophoresis, Gel, Two-Dimensional; D006825:Hybridomas; D046911:Macromolecular Substances; D051379:Mice; D008970:Molecular Weight; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D013601:T-Lymphocytes / Q000201:enzymology / Q000502:physiology* / Q000648:ultrastructure
D046911:Macromolecular Substances; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D011948:Receptors, Antigen, T-Cell; D011505:Protein-Tyrosine Kinases; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn