Endoplasmic reticulum cargo receptor that mediates the export of the yolk proteins from intestinal cells by recruiting cargos into COPII vesicles to facilitate their secretion (PubMed:29643117). Required for the endoplasmic reticulum export of the yolk protein vit-2, which is synthesized as a lipoprotein complex, from intestinal cells (PubMed:29643117). Involved in endoplasmic reticulum exit sites (ERES) organization (PubMed:29643117). Predominantly localizes at endoplasmic reticulum exit sites (ERES). The di-lysine motif confers endoplasmic reticulum localization for type I membrane proteins. High rate of embryonic and larval lethality (PubMed:29643117). Some mutants reach adulthood but display severe accumulation of vit-2 in large granule-like structures in intestinal cells (PubMed:29643117). Belongs to the SURF4 family.