trunk domain. COPII-coated vesicles carry proteins from the endoplasmic reticulum to the Golgi complex. This vesicular transport can be reconstituted by using three cytosolic components containing five proteins: the small GTPase Sar1p, the Sec23p/24p complex, and the Sec13p/Sec31p complex. This domain is known as the trunk domain and has an alpha/beta vWA fold and forms the dimer interface. Some members of this family possess a partial MIDAS motif that is a characteristic feature of most vWA domain proteins.