Mutational analysis of the Src SH3 domain: The same residues of the ligand binding surface are important for intra- and intermolecular interactions

摘要: The protein tyrosine kinase c-Src is negatively regulated by phosphorylation of Tyr527 in its C-terminal tail. repressed state achieved through intramolecular interactions involving the phosphorylated tail, Src homology 2 (SH2) domain and SH3 domain. Both SH2 domains have also been shown to mediate intermolecular interaction with several proteins. To test which amino acids are important for these interactions, whether intra- associations involve same residues, we carried out a detailed mutational analysis presumptive surface. All mutations conserved hydrophobic residues had an effect on both inter- domain, although not all were equally important. Chimeric molecules was replaced those spectrin or Lck showed derepressed activity, whereas chimera containing Fyn fully regulated. Since share characteristic domains, other must be specificity. Mutational non- semi-conserved RT n-Src loops that some involved interactions. Stable transfection selected mutants into NIH-3T3 cells despite elevated levels phosphotyrosine, morphologically normal, indicating required efficient transformation Src.