Adapter protein required for Golgi and endoplasmic reticulum biogenesis (PubMed:17141156). Involved in Golgi and endoplasmic reticulum maintenance during interphase and in their reassembly at the end of mitosis (PubMed:17141156). The complex formed with VCP has membrane fusion activity; membrane fusion activity requires USO1-GOLGA2 tethering and BET1L (PubMed:17141156). VCPIP1 is also required, but not its deubiquitinating activity (PubMed:17141156). Together with NSFL1C/p47, regulates the centrosomal levels of kinase AURKA/Aurora A during mitotic progression by promoting AURKA removal from centrosomes in prophase (PubMed:23649807). Also, regulates spindle orientation during mitosis (PubMed:23649807).