title: Structural basis for dimerization of the Grb10 Src homology 2 domain. Implications for ligand specificity.
abstract: Grb7, Grb10, and Grb14 are members of a distinct family of adapter proteins that interact with various receptor tyrosine kinases upon receptor activation. Proteins in this family contain several modular signaling domains including a pleckstrin homology (PH) domain, a BPS (between PH and SH2) domain, and a C-terminal Src homology 2 (SH2) domain. Although SH2 domains are typically monomeric, we show that the Grb10 SH2 domain and also full-length Grb10 gamma are dimeric in solution under physiologic conditions. The crystal structure of the Grb10 SH2 domain at 1.65-A resolution reveals a non-covalent dimer whose interface comprises residues within and flanking the C-terminal alpha helix, which are conserved in the Grb7/Grb10/Grb14 family but not in other SH2 domains. Val-522 in the BG loop (BG3) and Asp-500 in the EF loop (EF1) are positioned to interfere with the binding of the P+3 residue of a phosphopeptide ligand. These structural features of the Grb10 SH2 domain will favor binding of dimeric, turn-containing phosphotyrosine sequences, such as the phosphorylated activation loops in the two beta subunits of the insulin and insulin-like growth factor-1 receptors. Moreover, the structure suggests the mechanism by which the Grb7 SH2 domain binds selectively to pTyr-1139 (pYVNQ) in Her2, which along with Grb7 is co-amplified in human breast cancers.
authors.affiliation: Skirball Institute of Biomolecular Medicine and Department of Pharmacology, New York University School of Medicine, New York, New York 10016, USA.
authors.forename: Evan G
authors.initials: EG
authors.lastname: Stein
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Ghirlando
authors.forename: Stevan R
authors.initials: SR
authors.lastname: Hubbard
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D066246:ErbB Receptors / Q000737:chemistry / Q000378:metabolism; D051383:GRB10 Adaptor Protein; D051382:GRB7 Adaptor Protein; D006801:Humans; D008024:Ligands; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012996:Solutions; D013379:Substrate Specificity; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C099655:GRB14 protein, human; C495955:GRB7 protein, human; D008024:Ligands; D010446:Peptide Fragments; D011506:Proteins; D012996:Solutions; D051382:GRB7 Adaptor Protein; D051383:GRB10 Adaptor Protein; D066246:ErbB Receptors