May play a role in regulating membrane trafficking of cargo proteins. Together with ATP9A and MON2, regulates SNX3 retromer-mediated endosomal sorting of WLS away from lysosomal degradation. Homooligomer (PubMed:30213940). Heterotrimer with ATP9A and MON2; this interaction is retromer-independent (PubMed:30213940). Interacts with SNX3 (PubMed:30213940). Ubiquitously expressed. Overexpressed in lymphoblasts from Down syndrome patients. Abundantly expressed in developing central nervous system, with highest levels in cerebellum and lowest in telencephalon. Belongs to the dopey family.