Binding of Vitamin E in Mammalian Tumor Cells in Culture

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Abstract
Radioactive vitamin E (D-α-[5-methyl-3H]tocopherol) bound with the cytosol (100,000g supernatant), pellet (100,000g pellet), crude nuclear, and purified chromatin fractions from mouse neuroblastoma (NBP2) and rat glioma (C-6) cells in culture. The level and type of vitamin E binding proteins in the cytosol depended upon the cell type. When the cytosol proteins containing radioactive vitamin E were separated by gel filtration (Sepharose 4B gel), there were five protein peaks in neuroblastoma, three peaks in glioma, and one peak in mouse B-16 melanoma cells which contained bound radioactivity. The level of binding in the neuroblastoma cells was higher than that in glioma cells or melanoma cells. Vitamin E remained bound to the proteins from the cytosols of neuroblastoma and glioma even after denaturation and separation by electrophoresis. This suggests that vitamin E is tightly bound with the cytosol proteins. There was only one vitamin E binding protein in the pellet and nuclear fractions of NB, glioma, and melanoma cells. The significance of vitamin E binding proteins in the mechanism of the effect of vitamin E on mammalian cells in culture is unknown.