Demonstration that LSTRA cells have an elevated level of proteins phosphorylated on tyrosine residues

• Published in: FEBS letters 1987-09, Vol.222 (1), p.104-108
• Main Authors: Thom, Rebecca E., Casnellie, John E.
• Format: Article
• Language: English
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; Cell Line; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Humans; Immune Sera; Lymphoid cell; Molecular Weight; p210c-abl, form of the Abelson tyrosine protein kinase expressed in K562 cells; Phosphoproteins - analysis; Phosphorylation; Phosphotyrosine; Phosphotyrosine antibody; pp56lck, tyrosine protein kinase of M r 56000 found elevated in LSTRA cells; pp60src, the cellular homologue of the transforming protein of the Rous sarcoma virus; Protein-Tyrosine Kinases - metabolism; Transferases; Tyrosine - analogs & derivatives; Tyrosine - analysis; Tyrosine protein kinase
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(87)80200-4

The LSTRA cell line has been shown to have an exceptionally high level of a tyrosine protein kinase (pp56 lck). We now report that LSTRA cells also have a much higher level of proteins phosphorylated on tyrosine residues in comparison to several other cell lines with normal levels of pp56 lck. The level of phosphotyrosine-containing proteins in LSTRA cells was comparable to that seen in K562 cells, a cell line known to have a constitutively active tyrosine protein kinase. These results provide evidence that LSTRA cells have an elevated level of in vivo tyrosine protein kinase activity, probably due to the overexpression and activation of pp56 lck.