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, EFR3A probably acts as the membrane-anchoring component. Also involved in responsiveness to G-protein-coupled receptors; it is however unclear whether this role is direct or indirect. Component of a phosphatidylinositol 4-kinase (PI4K) complex, composed of PI4KA, EFR3 (EFR3A or EFR3B), TTC7 (TTC7A or TTC7B) and FAM126 (FAM126A or FAM126B). Palmitoylation anchors the protein to the plasma membrane. A small amount is observed in the cytosol. Widely expressed (PubMed:25380825). Expressed in neurons of the superior olivary complex of the auditory brainstem. Also expressed at lower levels in the cochlear nucleus, the lateral leminiscal nuclei and the inferior collicus (PubMed:15363888). Expression is reduced in animals with impaired hearing. Palmitoylated at its N-terminus, anchoring the protein to the plasma membrane. Belongs to the EFR3 family.