Binds alpha-tocopherol and enhances its transfer between separate membranes. Defects in TTPA are the cause of ataxia with isolated vitamin E deficiency (AVED). AVED is an autosomal recessive disease characterized by spinocerebellar degeneration. It causes ataxia and peripheral neuropathy that resembles Friedreich ataxia. AVED patients have markedly reduced plasma levels of vitamin E. Note: This description may include information from UniProtKB.