Stimulation through the T cell receptor induces Cbl association with Crk proteins and the guanine nucleotide exchange protein C3G.
We and others have recently identified Cbl, the protein product of the c-cbl protooncogene, as an early tyrosine kinase substrate upon T cell activation and have shown that Cbl forms in vivo complexes with Src family tyrosine kinases, Grb2 adaptor protein, and the p85 subunit of PI-3 kinase. Here we ... show that Cbl associates with all three forms of the human Crk protein, predominantly CrkL, following T cell receptor activation of Jurkat T cells. Association between Cbl and Crk proteins was confirmed in normal human peripheral blood-derived T cells. In vitro, Cbl was able to interact with the Crk SH2 domain but not the SH3 domain. A phosphopeptide corresponding to a potential Crk SH2 domain-binding motif in Cbl (pYDVP) specifically inhibited binding between Cbl and Crk SH2 domain. Anti-Cbl antibody completely immunodepleted the CrkL-associated 120kDa phosphotyrosyl polypeptide, suggesting that the recently described p130cas-related Crk-associated p116 of T cells may be Cbl. Consistent with this possibility, the 4F4 antibody used to characterize the p116 polypeptide cross-reacted with Cbl protein when it was resolved on one- or two-dimensional gels. CrkL was constitutively associated with a substantial amount of the guanine nucleotide exchange protein C3G, and a fraction of the C3G protein was coimmunoprecipitated with Cbl in activated Jurkat T cells. These results suggest the possibility that Cbl may participate in a signaling pathway that regulates guanine nucleotide exchange on small G-proteins in T cells.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Amino Acid Sequence, Crk-Associated Substrate Protein, Guanine Nucleotide Exchange Factors, Humans, Leucine Zippers, Lymphocyte Activation, Molecular Sequence Data, Nuclear Proteins, Phosphoproteins, Phosphotyrosine, Protein Binding, Proteins, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-cbl, Receptors, Antigen, T-Cell, Recombinant Proteins, Retinoblastoma-Like Protein p130, Signal Transduction, T-Lymphocytes, Tumor Cells, Cultured, Ubiquitin-Protein Ligases, src Homology Domains
Adaptor Proteins, Signal Transducing, Amino Acid Sequence, Crk-Associated Substrate Protein, Guanine Nucleotide Exchange Factors, Humans, Leucine Zippers, Lymphocyte Activation, Molecular Sequence Data, Nuclear Proteins, Phosphoproteins, Phosphotyrosine, Protein Binding, Proteins, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-cbl, Receptors, Antigen, T-Cell, Recombinant Proteins, Retinoblastoma-Like Protein p130, Signal Transduction, T-Lymphocytes, Tumor Cells, Cultured, Ubiquitin-Protein Ligases, src Homology Domains
J. Biol. Chem.
Date: Apr. 05, 1996
PubMed ID: 8626543
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