Required for retention of late Golgi membrane proteins. Component of the retrieval machinery that functions by direct interaction with the cytosolic tails of certain TGN membrane proteins during the sorting/budding process at the prevacuolar compartment. Binds phosphatidylinositol 3-phosphate (PtdIns(P3)) (By similarity). The PX domain binds phosphatidylinositol 3-phosphate which is necessary for peripheral membrane localization. Belongs to the sorting nexin family.