Acts as a component of endosomal retrieval machinery that is involved in protein transport from early endosomes to either recycling endosomes or the trans-Golgi network (By similarity). Mediates the recruitment of Golgi-associated retrograde protein (GARP) complex to the trans-Golgi network and controls early endosome-to-Golgi transport of internalized protein (By similarity). Promotes the recycling of internalized transferrin receptor (TFRC) to the plasma membrane through interaction with endosome-associated recycling protein (EARP) complex (By similarity). Controls proper insulin distribution and secretion, and retention of cargo in mature dense core vesicles (PubMed:3172165). Required for the stability of the endosome-associated retrograde protein (EARP) complex subunits and for proper localization and association of EARP with membranes (PubMed:3172165). Interacts with two multisubunit tethering complexes: EARP composed of VPS50, VPS51, VPS52 and VPS53 subunits and GARP complex composed of VPS51, VPS52, VPS53 and VPS54 subunits (PubMed:27440922, PubMed:27191843). Interacts with SNAP29 (PubMed:27191843). Ubiquitous. Highly expressed in brain, adipose tissue, spleen and kidney (at protein level). Belongs to the WD repeat EIPR1 family.