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Association of Src-like protein tyrosine kinases with the CD2 cell surface molecule in rat T lymphocytes and natural
G M Bell1, J B Bolen, J B Imboden
1Department of Medicine, Veterans Affairs Medical Center, San Francisco, California 94121.
Abstract:
The cell surface molecule CD2 has a signaling role in the activation of T lymphocytes and natural killer cells. Because perturbation of CD2 leads to the appearance of tyrosine-phosphorylated proteins, we investigated the possibility that CD2 associates with cytoplasmic protein tyrosine kinases. As determined by in vitro kinase assays and phosphoamino acid analysis, protein tyrosine kinase activity coprecipitated with CD2 from rat T lymphocytes, T lymphoblasts, thymocytes, interleukin-2-activated natural killer cells, and RNK-16 cells (a rat natural killer cell line). In each case, both p56lck and p59fyn were identified in the CD2 immunoprecipitate. In the thymus, the association between CD2 and these kinases occurred predominately in a small subset of thymocytes that had the cell surface phenotype of mature T cells, indicating that the association is a regulated event and occurs late in T-cell ontogeny. The finding that CD2 is associated with p56lck and p59fyn in detergent lysates suggests that interactions with these Src-like protein kinases play a critical role in CD2-mediated signal transduction.
Insights
The cell surface molecule CD2 associates with protein tyrosine kinases like p56lck and p59fyn in T lymphocytes and natural killer cells. This interaction is crucial for CD2-mediated signal transduction during T-cell activation.
Area of Science:
- Immunology
- Cell Biology
- Molecular Signaling
Background:
- CD2 is a cell surface molecule critical for T lymphocyte and natural killer cell activation.
- Perturbation of CD2 signaling results in tyrosine-phosphorylated proteins, suggesting kinase involvement.
Purpose of the Study:
- To investigate the association between CD2 and cytoplasmic protein tyrosine kinases.
- To elucidate the role of these interactions in CD2-mediated signal transduction.
Main Methods:
- In vitro kinase assays and phosphoamino acid analysis were employed.
- Immunoprecipitation of CD2 from various rat immune cell types was performed.
Main Results:
- Protein tyrosine kinase activity was consistently coprecipitated with CD2.
- p56lck and p59fyn were identified in CD2 immunoprecipitates from multiple cell types.
- The CD2-kinase association was observed late in T-cell development in thymocytes.
Conclusions:
- CD2 associates with p56lck and p59fyn protein tyrosine kinases.
- These interactions are likely critical for CD2-mediated signal transduction pathways.
- The association is a regulated event occurring late in T-cell ontogeny.