Interactions of Cbl with two adapter proteins, Grb2 and Crk, upon T cell activation

J Biol Chem. 1996 Mar 15;271(11):6159-63. doi: 10.1074/jbc.271.11.6159.

Abstract

Several recent studies have demonstrated that Grb2, composed entirely of SH2 and SH3 domains, serves as an adaptor protein in tyrosine kinase signaling pathways. Cb1, the protein product of c-cbl proto-oncogene, has been reported to be phosphorylated on tyrosine residues upon T cell receptor (TCR) engagement. Here we show that in unstimulated Jurkat cells Cbl is co-immunoprecipitated with monoclonal antibody against Grb2. However, in lymphocytes activated through the TCR, Cbl loses its ability to bind to Grb2 precipitated either with anti-Grb2 antibody or with an immobilized tyrosine phosphopeptide, Y1068-P, derived from the epidermal growth factor receptor. In vitro studies confirm that the ability of Cb1 to bind to both SH3 domains of Grb2 is strongly reduced in activated T lymphocytes. Investigation of the time course of Cbl dissociation from Grb2 reveals that it is transient and correlates with the kinetics of tyrosine phosphorylation of Cbl. Moreover, Cb1 is co-immunoprecipitated with Crk, another SH2/SH3 domain-containing protein, upon TCR stimulation. Tyrosine-phosphorylated Cbl binds exclusively to the SH2 domain of Crk. These results suggest that different adaptor proteins may have different roles in the regulation of c-cbl proto-oncogene product.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing*
  • Amino Acid Sequence
  • Binding Sites
  • Cell Line
  • GRB2 Adaptor Protein
  • Humans
  • Kinetics
  • Lymphocyte Activation
  • Molecular Sequence Data
  • Phosphorylation
  • Proteins / chemistry
  • Proteins / genetics
  • Proteins / metabolism*
  • Proto-Oncogene Mas
  • Proto-Oncogene Proteins / chemistry
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-cbl
  • Proto-Oncogene Proteins c-crk
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / metabolism*
  • Tyrosine / metabolism
  • Ubiquitin-Protein Ligases*
  • src Homology Domains

Substances

  • Adaptor Proteins, Signal Transducing
  • GRB2 Adaptor Protein
  • GRB2 protein, human
  • MAS1 protein, human
  • Proteins
  • Proto-Oncogene Mas
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-crk
  • Recombinant Fusion Proteins
  • Tyrosine
  • Proto-Oncogene Proteins c-cbl
  • Ubiquitin-Protein Ligases
  • CBL protein, human