A high-affinity Arg-X-X-Lys SH3 binding motif confers specificity for the interaction between Gads and SLP-76 in T cell signaling

Curr Biol. 2002 Aug 6;12(15):1336-41. doi: 10.1016/s0960-9822(02)01038-2.


A critical event in T cell receptor (TCR)-mediated signaling is the recruitment of hematopoietic-specific adaptor proteins that collect and transmit signals downstream of the TCR. Gads, a member of the Grb2 family of SH2 and SH3 domain-containing adaptors, mediates the formation of a complex between LAT and SLP-76 that is essential for signal propagation from the TCR. Here we examine the binding specificity of the Gads and Grb2 SH3 domains using peptide arrays and find that a nonproline-based R-X-X-K motif found in SLP-76 binds to the Gads carboxy-terminal SH3 domain with high affinity (K(D) = 240 +/- 45 nM). The Grb2 C-terminal SH3 domain also binds this motif, but with a 40-fold lower affinity than Gads. Single point mutations in either the relevant R (237) or K (240) completely abrogated SLP-76 association with Gads in vivo and impaired SLP-76 function. A chimeric Grb2 protein, possessing the C-terminal SH3 domain of Gads, was able to partially substitute for Gads in signaling downstream of the T cell receptor. These results provide a molecular explanation for the specific role of Gads in T cell receptor signaling, and identify a discrete subclass of SH3 domains whose binding is dependent on a core R-X-X-K motif.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing*
  • Amino Acid Sequence
  • Amino Acid Substitution
  • Arginine
  • Binding Sites
  • Carrier Proteins / chemistry
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • GRB2 Adaptor Protein
  • Interleukin-2 / genetics
  • Kinetics
  • Lysine
  • Mutagenesis, Site-Directed
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Phosphoproteins / chemistry
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Proteins / chemistry
  • Proteins / metabolism
  • Receptors, Antigen, T-Cell / immunology
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • T-Lymphocytes / immunology*
  • Transcription, Genetic
  • src Homology Domains*


  • Adaptor Proteins, Signal Transducing
  • Carrier Proteins
  • GRAP2 protein, human
  • GRB2 Adaptor Protein
  • Interleukin-2
  • Peptide Fragments
  • Phosphoproteins
  • Proteins
  • Receptors, Antigen, T-Cell
  • Recombinant Proteins
  • SLP-76 signal Transducing adaptor proteins
  • Arginine
  • Lysine