Binds alpha-tocopherol, enhances its transfer between separate membranes, and stimulates its release from liver cells (PubMed:7887897). Binds both phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 4,5-bisphosphate; the resulting conformation change is important for the release of the bound alpha-tocopherol (By similarity). Monomer and homotetramer. Phosphatidylinositol 4,5-bisphosphate binding induces the formation of homotetramers. Phosphatidylinositol 3,4-bisphosphate is less efficient in inducing tetramerization (By similarity). The disease is caused by variants affecting the gene represented in this entry.