Epidermal growth factor and epidermal growth factor receptor-dependent phosphorylation of a Mr = 34,000 protein substrate for pp60src |
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Authors: | P Ghosh-Dastidar C F Fox |
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Abstract: | A Mr = 34,000 protein present in the 100,000 X g supernatant fraction from A431 human epidermoid carcinoma cells is the major radiolabeled phosphate acceptor from gamma-32P]ATP in a cell-free system requiring epidermal growth factor (EGF) and EGF receptor kinase. This protein is immunoprecipitated by IgG directed against avian Mr = 34,000 cellular substrate for pp60src. Phosphoamino acid analysis of the Mr = 34,000 protein labeled with 32Pi from gamma-32P]ATP in a cell-free system requiring EGF and EGF receptor kinase yielded radiolabeled phosphotyrosine with no detectable radioactivity in phosphoserine or phosphothreonine. |
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