Component of a complex required to localize phosphatidylinositol 4-kinase (PI4K) to the plasma membrane. Component of a phosphatidylinositol 4-kinase (PI4K) complex, composed of PI4KA, EFR3 (EFR3A or EFR3B), TTC7 (TTC7A or TTC7B) and FAM126 (FAM126A or FAM126B). Expressed in the central nervous system. Expressed at much lower level in oligodendrocytes than in neurons. Belongs to the FAM126 family.