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Tyrosine-phosphorylated Cbl binds to Crk after T cell activation
S Sawasdikosol1, J H Chang, J C Pratt
1Division of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|July 1, 1996
Summary
The adapter protein Crk binds to the c-cbl proto-oncogene product, not Cas, after T cell activation. This Crk-Cbl interaction, mediated by Crk
Area of Science:
- Molecular Biology
- Cell Signaling
- Immunology
Background:
- Crk is an adapter protein involved in intracellular signaling pathways.
- Crk interacts with a 116 kDa phosphoprotein upon T cell receptor (TCR) activation.
Purpose of the Study:
- To identify the 116 kDa phosphoprotein associated with Crk after TCR activation.
- To elucidate the role of the Crk-associated protein in T cell signaling.
Main Methods:
- T cell activation and subsequent immunoprecipitation of Crk.
- Western blotting to detect phosphoproteins.
- In vitro binding assays using glutathione S-transferase (GST) fusion proteins.
- Phosphopeptide-binding studies.
Main Results:
- The Crk-associated p116 phosphoprotein is identified as the c-cbl proto-oncogene product, not Crk-associated substrate (Cas).
- Cbl, but not Cas, is tyrosine-phosphorylated after T cell activation.
- Tyrosine-phosphorylated Cbl associates with Crk via its SH2 domain.
- Crk's SH2 domain binds to a specific tyrosine-phosphorylated peptide of Cbl.
Conclusions:
- Crk associates with tyrosine-phosphorylated Cbl following TCR engagement.
- This interaction is mediated by the Crk SH2 domain.
- The Crk-Cbl association may link TCR signaling to Ras-related pathways, similar to Cbl-like molecules in C. elegans.