Chemical shift assignments and secondary structure of the Grb2 SH2 domain by heteronuclear NMR spectroscopy

The growth factor receptor-bound protein-2 (Grb2) is an adaptor protein that mediates signal transduction pathways. Chemical shift assignments were obtained for the SH2 domain of Grb2 by heteronuclear NMR spectroscopy, employing the uniformly C-13-/N-15-enriched protein as well as the protein containing selectively N-15-enriched amino acids. Using the Chemical Shift Index (CSI) method, the chemical shift indices of four nuclei, H-1(alpha), C-13(alpha), C-13(beta) and (CO)-C-13, were used to derive the secondary structure of the protein. Nuclear Overhauser enhancements (NOEs) were then employed to confirm the secondary structure. The CSI results were compared to the secondary structural elements predicted for the Grb2 SH2 domain from a sequence alignment [Lee et al. (1994) Structure, 2, 423-438]. The core structure of the SH2 domain contains an antiparallel beta-sheet and two alpha-helices. In general, the secondary structural elements determined from the CSI method agree well with those predicted from the sequence alignment.