Probable chaperone protein which facilitates trafficking and functional cell surface expression of some G-protein coupled receptors (GPCRs). Promotes functional expression of the bitter taste receptor TAS2R16 (By similarity). Also promotes functional expression of the opioid receptor heterodimer OPRD1-OPRM1 (PubMed:18836069). Interacts with TASR16 (By similarity). Interacts with OPRD1 and OPRM1; the interaction promotes cell surface localization of the OPDR1-OPRM1 heterodimer (PubMed:18836069). Expressed at low levels in olfactory neurons. By interferons. Belongs to the TMEM7 family.