Stimulation through the T cell receptor induces Cbl association with Crk proteins and the guanine nucleotide exchange protein C3G

J Biol Chem. 1996 Apr 5;271(14):8435-42. doi: 10.1074/jbc.271.14.8435.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

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 / metabolism*
  • Phosphoproteins / metabolism
  • Phosphotyrosine / metabolism
  • Protein Binding
  • Proteins / metabolism*
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-cbl
  • Receptors, Antigen, T-Cell / physiology*
  • Recombinant Proteins
  • Retinoblastoma-Like Protein p130
  • Signal Transduction
  • T-Lymphocytes / metabolism
  • Tumor Cells, Cultured
  • Ubiquitin-Protein Ligases*
  • src Homology Domains

Substances

  • Adaptor Proteins, Signal Transducing
  • BCAR1 protein, human
  • CRKL protein
  • Crk-Associated Substrate Protein
  • Guanine Nucleotide Exchange Factors
  • Nuclear Proteins
  • Phosphoproteins
  • Proteins
  • Proto-Oncogene Proteins
  • Receptors, Antigen, T-Cell
  • Recombinant Proteins
  • Retinoblastoma-Like Protein p130
  • Phosphotyrosine
  • Proto-Oncogene Proteins c-cbl
  • Ubiquitin-Protein Ligases
  • CBL protein, human