Involved in several stages of intracellular trafficking. Interacts with membranes containing phosphatidylinositol 3-phosphate (PtdIns(3P)) or phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2). Acts in part as component of the retromer membrane-deforming SNX-BAR subcomplex. The SNX-BAR retromer mediates retrograde transport of cargo proteins from endosomes to the trans-Golgi network (TGN) and is involved in endosome-to-plasma membrane transport for cargo protein recycling. The SNX-BAR subcomplex functions to deform the donor membrane into a tubular profile called endosome-to-TGN transport carrier (ETC). Can sense membrane curvature and has in vitro vesicle-to-membrane remodeling activity. Involved in retrograde endosome-to-TGN transport of lysosomal enzyme receptors (IGF2R, M6PR and SORT1). Plays a role in targeting ligand-activated EGFR to the lysosomes for degradation after endocytosis from the cell surface and release from the Golgi. Involvement in retromer-independent endocytic trafficking of P2RY1 and lysosomal degradation of protease-activated receptor-1/F2R. Promotes KALRN- and RHOG-dependent but retromer-independent membrane remodeling such as lamellipodium formation; the function is dependent on GEF activity of KALRN. Required for endocytosis of DRD5 upon agonist stimulation but not for basal receptor trafficking (By similarity). Predominantly forms heterodimers with BAR domain-containing sorting nexins SNX5, SNX6 and SNX32 (By similarity). Can self-associate to form homodimers (PubMed:11726276). The heterodimers are proposed to self-assemble into helical arrays on the membrane to stabilize and expand local membrane curvature underlying endosomal tubule formation. Thought to be a component of the originally described retromer complex (also called SNX-BAR retromer) which is a pentamer containing the heterotrimeric retromer cargo-selective complex (CSC), also described as vacuolar protein sorting subcomplex (VPS) and a heterodimeric membrane-deforming subcomplex formed between SNX1 or SNX2 and SNX5 or SNX6 (also called SNX-BAR subcomplex); the respective CSC and SNX-BAR subcomplexes associate with low affinity. Interacts with SNX5, SNX6, SNX32, VPS26A, VPS29, VPS35, DRD5, DENND5A, KALRN, RHOG (GDP-bound form). The interaction with SNX2 is reported controversially. Interacts with DNAJC13; prevented by presence of HGS. Interacts with HGS (By similarity). Enriched on tubular elements of the early endosome membrane. Binds preferentially to highly curved membranes enriched in phosphatidylinositol 3-phosphate (PtdIns(3P)) or phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2). Colocalized with SORT1 to tubular endosomal membrane structures called endosome-to-TGN transport carriers (ETCs) which are budding from early endosome vacuoles just before maturing into late endosome vacuoles. Colocalized with F-actin at the leading edge of lamellipodia in a KALRN-dependent manner. The BAR domain is able to sense membrane curvature upon dimerization. Membrane remodeling seems to implicate insertion of a N-terminal amphipathic helix (AH) in the membrane (By similarity). No visible phenotype. Mice are born at the expected Mendelian ratio and are fertile. Mice lacking both Snx1 and Snx2 die during embryonic development, around 9.5 and 11.5 dpc. Binds phosphatidylinositol 3-phosphate (PtdIns-(3)P) and phosphatidylinositol 3,5-bisphosphate (PtdIns-(3,5)P2) in liposome-based assays. Can bind PtdIns(3,4,5)P3 in protein:lipid overlay assays, but not in liposome-based assays (By similarity). Belongs to the sorting nexin family.