Acts as component of the GARP complex that is involved in retrograde transport from early and late endosomes to the trans-Golgi network (TGN). The GARP complex is required for the maintenance of protein retrieval from endosomes to the TGN, acid hydrolase sorting, lysosome function, endosomal cholesterol traffic and autophagy. VPS51 participates in retrograde transport of acid hydrolase receptors, likely by promoting tethering and SNARE-dependent fusion of endosome-derived carriers to the TGN. Acts as component of the EARP complex that is involved in endocytic recycling. The EARP complex associates with Rab4-positive endosomes and promotes recycling of internalized transferrin receptor (TFRC) to the plasma membrane. Component of the Golgi-associated retrograde protein (GARP) complex, also called VFT (VPS fifty-three) complex, composed of VPS51, VPS52, VPS53 and VPS54 (By similarity). Component of the endosome-associated retrograde protein (EARP) complex, composed of VPS51, VPS52, VPS53 and VPS50/Syndetin (By similarity). EIPR1 interacts with both EARP and GARP complexes and mediates the recruitment of the GARP complex to the trans-Golgi network (By similarity). Interacts with STX6 (By similarity). Interacts with VPS50 and VPS54 in an EIPR1-independent manner (By similarity). Localizes to the trans-Golgi network as part of the GARP complex, while it localizes to recycling endosomes as part of the EARP complex. Belongs to the VPS51 family.