SH2 domain specificity and activity modified by a single residue
Abstract
MANY intracellular targets of protein-tyrosine kinases possess Src homology 2 (SH2) domains that directly recognize phosphotyrosine-containing sites on autophosphorylated growth factor receptors and cytoplasmic proteins, and thereby mediate the activation of biochemical signalling pathways1-7. SH2 domains possess relatively well conserved residues that form the phosphotyrosine-binding pocket8-11, and more variable residues that are implicated in determining binding specificity by recognition of the three amino acids carboxy-terminal to phosphotyrosine (the +1 to +3 positions) 5,7,12,13. One such residue, occupying the EF1 position of the +3-binding pocket, is a Thr in the SH2 domain of the Src tyrosine kinase12, but is predicted to be a Trp in the SH2 domain of the Sem-5/drk/Grb2 adaptor protein5. Here we report that changing this residue in the Src SH2 domain from Thr to Trp switches its selectivity to resemble that of the Sem-5/drk/Grb2 SH2 domain. Furthermore, this mutant Src SH2 domain effectively substitutes for the SH2 domain of the Sem-5 protein in activation of the Ras pathway in vivo. These results identify a residue that can modify SH2 selectivity, and indicate that the biological activity of an SH2 domain correlates with its binding specificity.
- Publication:
-
Nature
- Pub Date:
- June 1994
- DOI:
- 10.1038/369502a0
- Bibcode:
- 1994Natur.369..502M