title: Grb2-independent recruitment of Gab1 requires the C-terminal lobe and structural integrity of the Met receptor kinase domain.
abstract: The Gab1 docking protein forms a platform for the assembly of a multiprotein signaling complex downstream from receptor tyrosine kinases. In general, recruitment of Gab1 occurs indirectly, via the adapter protein Grb2. In addition, Gab1 interacts with the Met/hepatocyte growth factor receptor in a Grb2-independent manner. This interaction requires a Met binding domain (MBD) in Gab1 and is essential for Met-mediated epithelial morphogenesis. The Gab1 MBD has been proposed to act as a phosphotyrosine binding domain that binds Tyr-1349 in the Met receptor. We show that a 16-amino acid motif within the Gab1 MBD is sufficient for interaction with the Met receptor, suggesting that it is unlikely that the Gab1 MBD forms a structured domain. Alternatively, the structural integrity of the Met receptor, and residues upstream of Tyr-1349 located in the C-terminal lobe of the kinase domain, are required for Grb2-independent interaction with the Gab1 MBD. Moreover, the substitution of Tyr-1349 with an acidic residue allows for the recruitment of the Gab1 MBD and for phosphorylation of Gab1. We propose that Gab1 and the Met receptor interact in a novel manner, such that the activated kinase domain of Met and the negative charge of phosphotyrosine 1349 engage the Gab1 MBD as an extended peptide ligand.
authors.affiliation: Department of Biochemistry, Molecular Oncology Group, McGill University Health Centre, Montreal, Quebec H3A 1A1, Canada.
authors.forename: Lisa S
authors.initials: LS
authors.lastname: Lock
authors.forename: Melanie M
authors.initials: MM
authors.lastname: Frigault
authors.forename: Caroline
authors.initials: C
authors.lastname: Saucier
authors.forename: Morag
authors.initials: M
authors.lastname: Park
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D015153:Blotting, Western; D002460:Cell Line; D051380:GRB2 Adaptor Protein; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism*; D019859:Proto-Oncogene Proteins c-met / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D014443:Tyrosine / Q000737:chemistry
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C098587:GAB1 protein, human; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D008024:Ligands; D010455:Peptides; D010750:Phosphoproteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D014443:Tyrosine; D005982:Glutathione Transferase; D019859:Proto-Oncogene Proteins c-met