Efficient cell transformation by the Tpr-Met oncoprotein is dependent upon tyrosine 489 in the carboxy-terminus.
The receptor for hepatocyte growth factor/scatter factor (HGF/SF) was originally identified as an oncogene, Tpr-Met, which consists of the cytoplasmic tyrosine kinase domain of the HGF/SF receptor (Met) fused down-stream of sequences encoded by the tpr gene. As a consequence of this rearrangement the Tpr-Met fusion oncoprotein is localized to the cytoplasm and is a constitutively activated kinase. To identify signalling pathways important for Tpr-Met-mediated cell transformation we have generated tyrosine to phenylalanine mutants of Tpr-Met that are compromised in their ability to transform Fischer rat 3T3 (Fr3T3) cells in culture. We show that a single tyrosine residue in the carboxy terminus of Tpr-Met (residue 489) is essential for efficient transformation of Fr3T3 cells by this oncoprotein. Mutation of tyrosine 489 to phenylalanine does not affect the exogenous kinase activity of the Tpr-Met oncoprotein toward casein, but it impairs the ability of the mutant protein to bind to and activate phosphatidylinositol 3 kinase in vivo and completely abolishes the in vivo association with the Grb2 adaptor protein as well as the association and/or phosphorylation of an unknown protein of 110 kDa. These data are consistent with a single tyrosine residue in the Tpr-Met oncoprotein being essential for the activation of several signalling pathways which lead to the transformation of Fr3T3 fibroblasts.
Fixman
E D
ED
Royal Victoria Hospital, Department of Medicine, McGill University, Montreal, Quebec, Canada.
Naujokas
M A
MA
Rodrigues
G A
GA
Moran
M F
MF
Park
M
M
D019870:1-Phosphatidylinositol 4-Kinase; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002364:Caseins / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D002478:Cells, Cultured; D066246:ErbB Receptors / Q000378:metabolism; D051380:GRB2 Adaptor Protein; D017228:Hepatocyte Growth Factor / Q000502:physiology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D019869:Phosphatidylinositol 3-Kinases; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D019859:Proto-Oncogene Proteins c-met; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000502:physiology*; D014443:Tyrosine / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D002364:Caseins; D051380:GRB2 Adaptor Protein; C495950:Grb2 protein, rat; D011506:Proteins; D011518:Proto-Oncogene Proteins; D014443:Tyrosine; D017228:Hepatocyte Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D019870:1-Phosphatidylinositol 4-Kinase; D066246:ErbB Receptors; D019859:Proto-Oncogene Proteins c-met; D020794:Receptor Protein-Tyrosine Kinases