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 (By similarity). Required for vacuolar targeting and cellular trafficking. Involved in the regulation of vascular tissue patterning, probably by regulating PIN1 expression pattern, thus modulating auxin flux. Important to prevent PIN1 accumulation within margin cells, possibly by targeting PIN1 to the lytic vacuole. Regulates PIN1 and ATHB8 expression pattern in secondary veins (PubMed:24757006). Component of the Golgi-associated retrograde protein (GARP) complex, composed by VPS51, VPS52, VPS53 and VPS54. Component of the endosome-associated retrograde protein (EARP) complex, composed of VPS51, VPS52, VPS53 and VPS50 (By similarity). Interacts with VPS52 (PubMed:24757006). Localizes to the trans-Golgi network as part of the GARP complex, while it localizes to recycling endosomes as part of the EARP complex. Expressed in primary and lateral roots, shoots of seedlings and flowers. In leaves, first observed at low levels in a diffuse pattern 3.5 days after germination (DAG), spreads throughout much of the lamina by 4 DAG and becomes increasingly restricted to presumptive veins from 5 to 8 DAG. Confined in epidermal cells of the proximal margins in mature leaves. Leaf vascular tissue patterning defects: simpler leaf venation with distal non-meeting of the secondary veins and fewer higher order veins, a narrower leaf with prominent serrations, and reduced root and shoot growth. Normal early endocytic events, but disrupted cellular trafficking. Reduced vacuolar targeting resulting in expanded expression of PIN1 in leaf margins and altered expression pattern of PIN1 and ATHB8 in secondary veins. Belongs to the VPS51 family.