This review summarizes one portion of the research for which the author received the Pharmaceutical Society of Japan Award. The complete title of the awarded research is “Pharmacological Studies on Metabolism and Functions of Biomembrane Lipids”. Because the awarded research is a very broad study, this review describes the discovery, physiological functions, and congenital defects of α-tocopherol transfer protein (α-TTP), a critical factor in determining the transport of vitamin E in the body, which has been the focus of the author's work throughout his research career.
Vitamin
E (α-tocopherol) is the most important
lipid-soluble antioxidant in humans. The author identified a soluble protein
that specifically binds α-tocopherol
and named it α-tocopherol transfer protein (α-TTP). He found that α-TTP is a major
determinant of vitamin E levels in the body and that its mutation causes severe
vitamin E deficiency. α-TTP catalyzes intracellular vectorial transport of vitamin E by exchange with phosphatidylinositol
phosphates (PIPs), and this mechanism may be applicable to other intracellular lipid
transfer proteins.