title: A conserved DpYR motif in the juxtamembrane domain of the Met receptor family forms an atypical c-Cbl/Cbl-b tyrosine kinase binding domain binding site required for suppression of oncogenic activation.
abstract: The activation and phosphorylation of Met, the receptor tyrosine kinase (RTK) for hepatocyte growth factor, initiates the recruitment of multiple signaling proteins, one of which is c-Cbl, a ubiquitin-protein ligase. c-Cbl promotes ubiquitination and enhances the down-modulation of the Met receptor and other RTKs, targeting them for lysosomal sorting and subsequent degradation. The ubiquitination of Met by c-Cbl requires the direct interaction of the c-Cbl tyrosine kinase binding (TKB) domain with tyrosine 1003 in the Met juxtamembrane domain. Although a consensus for c-Cbl TKB domain binding has been established ((D/N)XpYXX(D/E0phi), this motif is not present in Met, suggesting that other c-Cbl TKB domain binding motifs may exist. By alanine-scanning mutagenesis, we have identified a DpYR motif including Tyr(1003) as being important for the direct recruitment of the c-Cbl TKB domain and for ubiquitination of the Met receptor. The substitution of Tyr(1003) with phenylalanine or substitution of either aspartate or arginine residues with alanine impairs c-Cbl-recruitment and ubiquitination of Met and results in the oncogenic activation of the Met receptor. We demonstrate that the TKB domain of Cbl-b, but not Cbl-3, binds to the Met receptor and requires an intact DpYR motif. Modeling studies suggest the presence of a salt bridge between the aspartate and arginine residues that would position pTyr(1003) for binding to the c-Cbl TKB domain. The DpYR motif is conserved in other members of the Met RTK family but is not present in previously identified c-Cbl-binding proteins, identifying DpYR as a new binding motif for c-Cbl and Cbl-b.
authors.affiliation: Department of Biochemistry, Medicine, and Oncology, McGill University, Montréal, Québec H3A 1A1, Canada.
authors.forename: Pascal
authors.initials: P
authors.lastname: Peschard
authors.forename: Noboru
authors.initials: N
authors.lastname: Ishiyama
authors.forename: Tong
authors.initials: T
authors.lastname: Lin
authors.forename: Stan
authors.initials: S
authors.lastname: Lipkowitz
authors.forename: Morag
authors.initials: M
authors.lastname: Park
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D000818:Animals; D001216:Asparagine / Q000378:metabolism; D001224:Aspartic Acid / Q000378:metabolism; D001665:Binding Sites; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D004789:Enzyme Activation; D006801:Humans; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D019859:Proto-Oncogene Proteins c-met / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D011518:Proto-Oncogene Proteins; D025801:Ubiquitin; D001224:Aspartic Acid; D014443:Tyrosine; D001216:Asparagine; C492211:CBLB protein, human; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D019859:Proto-Oncogene Proteins c-met; C067419:CBL protein, human; C119570:CBLC protein, human