Activation of Src in human breast tumor cell lines: elevated levels of phosphotyrosine phosphatase activity that preferentially recognizes the Src carboxy terminal negative regulatory tyrosine 530
| Autor: | Andrew Pang, Jerry H. Wang, Heung-Chin Cheng, Denise Durda, Cay Egan, Donald J. Fujita |
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| Rok vydání: | 1999 |
| Předmět: |
Phosphopeptides
Cancer Research Phosphatase Breast Neoplasms Cell Cycle Proteins Protein Tyrosine Phosphatase Non-Receptor Type 11 Receptors Cell Surface Protein tyrosine phosphatase Biology medicine.disease_cause SH2 domain Substrate Specificity Phosphoprotein Phosphatases Tumor Cells Cultured Genetics medicine Humans cdc25 Phosphatases Phosphorylation Tyrosine Molecular Biology Protein Tyrosine Phosphatase Non-Receptor Type 6 Receptor-Like Protein Tyrosine Phosphatases Class 4 Intracellular Signaling Peptides and Proteins Molecular biology Peptide Fragments src-Family Kinases Receptor-Like Protein Tyrosine Phosphatases Biochemistry Female Protein Tyrosine Phosphatases Carcinogenesis Proto-oncogene tyrosine-protein kinase Src |
| Zdroj: | Oncogene. 18:1227-1237 |
| ISSN: | 1476-5594 0950-9232 |
| Popis: | Elevated levels of Src kinase activity have been reported in a number of human cancers, including colon and breast cancer. We have analysed four human breast tumor cell lines that exhibit high levels of Src kinase activity, and have determined that these cell lines also exhibit a high level of a phosphotyrosine phosphatase activity that recognizes the Src carboxy-terminal P-Tyr530 negative regulatory site. Total Src kinase activity in these cell lines is elevated as much as 30-fold over activity in normal control cells and specific activity is elevated as much as 5.6-fold. When the breast tumor cells were grown in the presence of the tyrosine phosphatase inhibitor vanadate, Src kinase activity was reduced in all four breast tumor cell lines, suggesting that Src was being activated by a phosphatase which could recognize the Tyr530 negative regulatory site. In fractionated cell extracts from the breast tumor cells, we found elevated levels of a membrane associated tyrosine phosphatase activity that preferentially dephosphorylated a Src family carboxy-terminal phosphopeptide containing the regulatory tyrosine 530 site. Src was hypophosphorylated in vivo at tyrosine 530 in at least two of the tumor cell lines, further suggesting that Src was being activated by a phosphatase in these cells. In preliminary immunoprecipitation and antibody depletion experiments, we were unable to correlate the major portion of this phosphatase activity with several known phosphatases. |
| Databáze: | OpenAIRE |
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