Lactoperoxidase-catalyzed iodination of membrane proteins in normal and neoplastic epidermal cells

Cell surface proteins of normal human, mouse, and rat cells in primary culture, of human basal cell carcinoma, and of carcinogen-transformed cell lines were examined by lactoperoxidase-catalyzed iodination. Autoradiography was used to record the distribution of label in the polypeptide subunits separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. There was no significant difference in the results for normal cells of human, mouse, and rat. On the other hand, carcinogen-transformed mouse cells had many more labeled polypeptide bands of widely distributed molecular weights. The iodination profiles from human basal cell carcinoma cells were much more akin to those from normal cells than to those from carcinogen-transformed cells. Treatment of iodinated cells with proteolytic enzymes visibly altered the polypeptide bands.