Vitamin E: beyond antioxidant function.

Vitamin E, a potent peroxyl radical scavenger, is a chain-breaking antioxidant that prevents the propagation of free radical damage in biological membranes. We consider the evidence for potential sites in cellular metabolism and signal transduction where vitamin E may have a structure-specific role in addition to its antioxidant function. The roles of tocopherol-binding proteins in cellular trafficking of vitamin E, especially the incorporation of RRR-alpha-tocopherol into nascent lipoproteins, and the delivery of RRR-alpha-tocopherol to the nucleus are considered. We discuss the functions of vitamin E both in the inhibition and potentiation of arachidonic acid metabolism. The interactions of vitamin E during cell proliferation and differentiation are also evaluated. These functions of vitamin E raise new questions and represent new and exciting areas for research in cell regulation with physiologic implications.