PURIFICATION AND PARTIAL CHARACTERIZATION OF AN ALPHA-TOCOPHEROL-BINDING PROTEIN FROM RABBIT HEART CYTOSOL

An alpha-tocopherol-binding protein has been isolated and purified fro m rabbit heart cytosol. The purified protein had an apparent molecular mass of 14,200, as derived from SDS-PAGE. The content of the protein in rabbit heart was around 11.8 mug per g of tissue. The binding of al pha-tocopherol to the purified protein was rapid, reversible, and satu rable. Neither gamma nor delta tocopherol could displace the bound alp ha-tocopherol from the protein, suggesting a high specificity for alph a-tocopherol. Alpha-Tocopherol-binding protein did not bind oleate. Tr ansfer of alpha-tocopherol from liposomes to mitochondria was stimulat ed 8-fold in the presence of the binding protein, suggesting that this protein may be involved in the intracellular transport of alpha-tocop herol in the heart.