[Role of the cytosolic factor in the interaction of [3H] alpha-tocopherol with rat liver nuclei].

A protein fraction (Mr = 30-70 kD) specifically binding [3H]alpha-tocopherol was isolated from rat liver cytosol. Using high performance ion exchange chromatography, this fraction was separated into acid and alkaline protein subfractions. Acid proteins make up to 41% of the total protein pool and they bind the label 8 times more intensively than the alkaline ones. Cytosol and its protein fraction with an average molecular mass increase 2.2-2.5-fold the binding of labeled vitamin E to isolated liver nuclei. It is concluded that the cytosolic proteins having a medium molecular mass are involved in tocopherol interaction with the nuclei.