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Purified EGF receptor-kinase interacts specifically with antibodies to Rous sarcoma virus transforming protein
Abstract:
Transformation by several RNA tumour viruses seems to be mediated by virally coded protein kinases which specifically phosphorylate tyrosine. A tyrosine-specific protein kinase also seems to be involved in the mitogenic action of epidermal growth factor (EGF). This EGF-stimulated kinase activity is closely associated with the EGF receptor, with which it copurifies during EGF-affinity chromatography. Because both the virus- and EGF-stimulated tyrosine kinases may be involved in stimulation of cell growth, and because the viral kinases may be antigenically related to normal cell proteins, we examined the interaction of antibodies to viral tyrosine kinases with the affinity-purified EGF receptor-kinase preparation. We report here that the receptor-kinase specifically phosphorylates antibodies directed against the transforming protein kinase pp60src of Rous sarcoma virus. However, none of these antibodies, including those which cross-react with the normal cellular homologue of pp60src (pp60sarc), precipitate the receptor-kinase. These results suggest that the EGF receptor-kinase is related to, but probably not identical with, pp60sarc.
Insights
This study investigates the relationship between viral tyrosine kinases and the epidermal growth factor (EGF) receptor-kinase. Results suggest the EGF receptor-kinase is related to, but not identical with, the Rous sarcoma virus transforming protein kinase pp60src.
Area of Science:
- Molecular Biology
- Virology
- Cell Signaling
Background:
- RNA tumor viruses utilize virally encoded protein kinases for transformation, specifically phosphorylating tyrosine residues.
- Tyrosine-specific protein kinases are implicated in the mitogenic effects of epidermal growth factor (EGF), closely associated with the EGF receptor.
Purpose of the Study:
- To investigate the potential relationship between viral tyrosine kinases and the EGF receptor-kinase.
- To examine the interaction of antibodies against viral tyrosine kinases with the affinity-purified EGF receptor-kinase.
Main Methods:
- Affinity chromatography was used to purify the EGF receptor-kinase.
- Antibodies against the Rous sarcoma virus transforming protein kinase pp60src and its cellular homologue pp60sarc were employed.
- Phosphorylation assays were conducted to assess kinase activity.
Main Results:
- The EGF receptor-kinase specifically phosphorylates antibodies raised against the Rous sarcoma virus transforming protein kinase pp60src.
- Antibodies that cross-react with the cellular homologue pp60sarc did not precipitate the EGF receptor-kinase.
- These findings indicate a relationship but not identity between the EGF receptor-kinase and pp60sarc.
Conclusions:
- The EGF receptor-kinase shares similarities with viral tyrosine kinases like pp60src.
- While related, the EGF receptor-kinase is likely a distinct entity from pp60sarc.
- Further research is needed to elucidate the precise nature of the EGF receptor-kinase and its role in cell growth regulation.