Detection of phosphorylated retTPC oncogene product in cytoplasm.
The product of the retTPC oncogene, an activated form of the ret proto-oncogene found in human papillary thyroid carcinomas, was identified as a 57-kDa protein (p57retTPC) by Western blotting with a polyclonal antibody raised by an oligopeptide corresponding to the carboxy-terminal region of the ret proto-oncogene product. Subcellular fractionation experiments using NIH3T3 cell transformants induced by the retTPC cDNA showed that p57retTPC was localized in a soluble cytoplasmic fraction, whereas the ret proto-oncogene products expressed in a neuroblastoma cell line were present in a membrane fraction. Immunostaining also demonstrated that p57retTPC is localized in the cytoplasm. Immunoprecipitation with anti-phosphotyrosine antibody followed by Western blotting revealed that p57retTPC is constitutively phosphorylated, whereas the ret proto-oncogene products are not. These findings suggest that p57retTPC has an aberrant tyrosine kinase activity resulting in autophosphorylation associated with change in its location.
Ishizaka
Y
Y
Carcinogenesis Division, National Cancer Center Research Institute, Tokyo, Japan.
Shima
H
H
Sugimura
T
T
Nagao
M
M
D000595:Amino Acid Sequence; D000818:Animals; D002291:Carcinoma, Papillary / Q000737:chemistry; D002461:Cell Line, Transformed; D003593:Cytoplasm / Q000737:chemistry; D029721:Drosophila Proteins; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D015514:Oncogene Proteins, Fusion / Q000032:analysis; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000032:analysis* / Q000276:immunology; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; D013347:Subcellular Fractions / Q000737:chemistry; D013964:Thyroid Neoplasms / Q000737:chemistry; D014407:Tumor Cells, Cultured
D029721:Drosophila Proteins; C000715470:MAS1 protein, human; D015514:Oncogene Proteins, Fusion; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; C416649:Ret protein, Drosophila; C494999:Ret protein, mouse