Increase of phosphotyrosine-containing proteins in human carcinomas

Immunofluorescent (IF) staining with monoclonal antibody to O-phosphotyrosine (PTYR) has shown that a variety of human carcinomas (liver, esophagus, stomach, lung, colon and breast) have increased amounts of PTYR-containing proteins (PTYR-proteins), which are localized in cytoplasmic regions and nucleolus-like structures of the carcinoma cells. PTYR-proteins were isolated from carcinomas of the liver, stomach and esophagus, and also from normal regions of these organs by immunoaffinity chromatography with polyclonal antibodies to PTYR. They were then labeled with 125I and analyzed by gel electrophoresis. Twenty-eight species of PTYR-proteins in a molecular weight range from 310,000 to 23,000 were detected, of which the major 16 species were confirmed to contain 125I-labeled diiodo-O-phosphotyrosine residues. All the PTYR-proteins found in carcinomas were also present, though at much lower levels, in normal regions of the respective organs.