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

Kris A. Reedquist, Toru Fukazawa, Govindaswamy Panchamoorthy, Wallace Y. Langdon, Steven E. Shoelson, Brian J. Druker, Hamid Band

Research output: Contribution to journalArticle

158 Scopus citations

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 120-kDa phosphotyrosyl polypeptide, suggesting that the recently described p130(cas)-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.

Original languageEnglish (US)
Pages (from-to)8435-8442
Number of pages8
JournalJournal of Biological Chemistry
Volume271
Issue number14
DOIs
StatePublished - Apr 5 1996

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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