Avian sarcoma virus-transforming protein, pp60src shows protein kinase activity specific for tyrosine
摘要：
The protein responsible for malignant transformation by avian sarcoma viruses (ASVs) has been identified as a phos-phoprotein of molecular weight 60,000 designated pp60 src (refs 1–4). It has been suggested that this protein has a functional role in cellular transformation involving the phosphorylation of cellular proteins, for it was discovered that specific immunoprecipitates from ASV-transformed cells that contain pp60src catalysed the transfer of phosphate from [γ- 32 P]ATP to the heavy chain of rabbit immunoglobulin 5,6 . Additional studies involving the cell-free synthesis of the ASV src protein further demonstrated that the presence of the src polypeptide correlated with that presence of a phosphotransf erase activity 7 . Our studies, involving the biochemical purification of this protein, have demonstrated that the ASV-transforming gene product, pp60 src , is itself a protein kinase. We have purified the pp60 src protein approximately 5,000-fold using either conventional ion-exchange chromatography or immunoaffinity chromatography 8,9 . The resultant partially purified preparations contain a cyclic AMP-independent protein kinase activity 8 . We report here that the soluble phosphotransferase activity of partially purified pp60 src results in the phosphorylation of exclusively tyrosine residues in a variety of proteins that serve as substrates.
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DOI：
10.1038/285167a0
被引量：
年份：
1980
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