Protein tyrosine kinase activities of the epidermal growth factor receptor and ErbB proteins: correlation of oncogenic activation with altered kinetics
Document Type
Journal ArticlePublication Date
1992-05-01Keywords
3T3 CellsAdenosine Triphosphate
Animals
*Cell Transformation, Neoplastic
Chickens
Immune Sera
Kinetics
Mice
Phosphorylation
Protein-Tyrosine Kinases
Proto-Oncogene Proteins
*Proto-Oncogenes
Receptor, Epidermal Growth Factor
Recombinant Fusion Proteins
Substrate Specificity
Life Sciences
Medicine and Health Sciences
Metadata
Show full item recordAbstract
We have compared the protein tyrosine kinase activities of the chicken epidermal growth factor receptor (chEGFR) and three ErbB proteins to learn whether cancer-activating mutations affect the kinetics of kinase activity. In immune complex assays performed in the presence of 15 mM Mn2+, ErbB proteins and the chEGFR exhibited highly reproducible tyrosine kinase activity. Under these conditions, the ErbB and chEGFR proteins had similar apparent Km [Km(app)] values for ATP. The ErbB proteins appeared to be activated, as they had at least 3-fold-higher relative Vmax(app) for autophosphorylation and approximately 2-fold higher relative Vmax(app) for the phosphorylation of the exogenous substrate TK6 (a bacterially expressed fusion protein containing the C-terminal domain of the human EGFR). The ErbB kinases had both higher Km(app) and higher Vmax(app) for the phosphorylation of the exogenous substrate TK6 than did the chEGFR. The ratios of the Vmax(app) to the Km(app) for TK6 phosphorylation suggested that the ErbB proteins had lower catalytic efficiencies for the exogenous substrate than did the chEGFR. The three tested ErbB proteins had cytoplasmic domain mutations that conferred distinctive disease potentials. These mutations did not affect the kinetics for the phosphorylation of the exogenous substrate TK6. Two of the ErbB proteins contained all of the sites used for autophosphorylation. In these, a mutation that broadened oncogenic potential to endothelial cells caused an additional increase in Vmax(app) for autophosphorylation. Thus, mutations that change the EGFR into an ErbB oncogene cause multiple changes in the kinetics of protein tyrosine kinase activity.Source
Mol Cell Biol. 1992 May;12(5):2010-6.Permanent Link to this Item
http://hdl.handle.net/20.500.14038/38599PubMed ID
1314948Related Resources
Link to Article in PubMedCollections
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