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 (PubMed:27440922). 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 (PubMed:27440922). Promotes the recycling of internalized transferrin receptor (TFRC) to the plasma membrane through interaction with endosome-associated recycling protein (EARP) complex (PubMed:27440922). Controls proper insulin distribution and secretion, and retention of cargo in mature dense core vesicles (By similarity). Required for the stability of the endosome-associated retrograde protein (EARP) complex subunits and for proper localization and association of EARP with membranes (By similarity). . This is the function of EIPR1 (EARP complex and GARP complex interacting protein 1, ENSG00000032389).