Component of a complex required to localize phosphatidylinositol 4-kinase (PI4K) to the plasma membrane. The complex acts as a regulator of phosphatidylinositol 4-phosphate (PtdIns(4)P) synthesis. In the complex, plays a central role in bridging PI4KA to EFR3B and FAM126A, via direct interactions (PubMed:26571211). Component of a phosphatidylinositol 4-kinase (PI4K) complex, composed of PI4KA, EFR3 (EFR3A or EFR3B), TTC7 (TTC7A or TTC7B) and FAM126 (FAM126A or FAM126B) (PubMed:23229899). Interacts with PI4KA, interaction is direct (PubMed:26571211). Interacts with EFR3 (EFR3A or EFR3B), interaction is direct (PubMed:26571211). Interacts with FAM126 (FAM126A or FAM126B), interaction is direct (PubMed:26571211). Association with the PI4K complex is strongly reduced by TMEM150A (PubMed:25608530). Localizes to the cytosol and is recruited to the plasma membrane following interaction with EFR3 (EFR3A or EFR3B) (PubMed:23229899). Truncated N-terminus.