Plays a role in transport between endoplasmic reticulum and Golgi. In pancreatic beta cells, required to transport proinsulin from endoplasmic reticulum into the Golgi. Interacts with the COPII coat components Sec23 (SEC23A and/or SEC23B) and Sec24 (SEC24A and/or SEC24B) (By similarity). Interacts with YIF1A (By similarity). May interact with RAB1A (By similarity). Interacts with YIPF3 and YIPF4 (By similarity). Enriched at the endoplasmic reticulum exit sites (PubMed:15254263). Incorporated into COPII coated vesicles (By similarity). Ubiquitously expressed. Belongs to the YIP1 family.