Quantitative analysis of Grb2-Sos1 interaction: The N-terminal SH3 domain of Grb2 mediates affinity

L. Sastry, W. Lin, W. T. Wong, P. P. Di Fiore, C. A. Scoppa, C. R. King

Research output: Contribution to journalArticlepeer-review


Grb2 is an adaptor protein that links receptor and cytoplasmic tyrosine kinases to the Ras signalling pathway by binding the Ras-specific guanine nucleotide exchange factor, Sos1, through its SH3 domains. The Grb2-SH3 domain binding has been localized to the carboxy-terminal two hundred amino acids of Sos1 (Sos1-c). By using real time biospecific interaction analysis (BIAcore), we studied the kinetic parameters and binding affinity of the Grb2-Sos1-c interaction. The binding of Grb2 to Sos1-c is a high affinity interaction with a moderate association rate (9.45 x 104 per M per s), a slow dissociation rate (13.8 x 10-5 s), and an affinity constant of 1.48 nM. BIAcore measurements on isolated N-terminal and C-terminal SH3 domains (NSH3 and CSH3) further indicate that the high affinity Grb2-Sos1-c interaction is primarily mediated through the NSH3 domain (K(d) = 1.68 nM). The CSH3 domain shows substantially reduced binding to Sos1-c in these measurements. Inhibition studies with BIAcore using proline rich peptides derived from the C-terminus of Sos1 show that there is a single major binding site for Grb2 in Sos1, This binding site is contained within the peptide N20, which corresponds to amino acids 1143-1162 of Sos1. This peptide completely blocks the Grb2-Sos1-c and NSH3-Sos1-c interactions with IC50 values of 8 μM and 4 μM respectively. The discrete interaction between the NSH3 domain and the N20 peptide may be amenable for drug discovery through screening or peptidomimetic approaches.

Original languageEnglish
Pages (from-to)1107-1112
Number of pages6
Issue number6
Publication statusPublished - 1995


  • BIAcore
  • Grb2
  • Kinetics
  • Sos1
  • SPR

ASJC Scopus subject areas

  • Cancer Research
  • Genetics
  • Molecular Biology


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