Constituent of COPII-coated endoplasmic reticulum-derived transport vesicles. Required for efficient transport of a subset of secretory proteins to the Golgi (PubMed:11157978, PubMed:12426381). The C-terminal Ile-Leu motif is required for exit from the endoplasmic reticulum (PubMed:12426381). Facilitates retrograde transport from the Golgi to the endoplasmic reticulum (PubMed:12426381). Interacts with ERV46. Recycles between endoplasmic reticulum and Golgi. Resides in the endoplasmic and Golgi compartments, and then packaged into endoplasmic reticulum derived vesicles. Present with 3000 molecules/cell in log phase SD medium. Belongs to the ERGIC family.