| Abstract: | Salt and detergent extracts of xenografted human embryonic carcinoma and a human yolk sac carcinoma were fractionated on different sets of Sepharose columns covalently derivatized with lactose, asialofetuin, melibiose, mannan and fucose. Successive elution by chelating reagent and specific sugar resulted in isolation of endogenous Ca2+-dependent and Ca2+-independent carbohydrate-binding proteins, as analyzed by gel electrophoresis. The salt extracts of the embryonic carcinoma contained a Ca2+-dependent carbohydrate-binding protein at Mr66,000, that was undetectable in yolk sac tumor extracts. Also, a Ca2+-independent fucose-binding protein at Mr62,000 could be purified. In general, the pattern of carbohydrate-binding proteins showed quantitative and qualitative differences as compared to normal tissue. The carbohydrate-binding proteins were assayable as agglutinin and showed no enzymatic activity. They can thus be defined as lectins. Their presence within certain stages of differentiation and developmental regulation may contribute to improvement of the classification, diagnosis and therapy of this tumor class. These new lectins may also be functionally related to the stage-specific embryonic antigens like SSEA-1. |
