The nuclear pore complex (NPC) is a structure that spans the nuclear envelope and provides a conduit between the nucleus and cytoplasm for the nucleocytoplasmic transport of macromolecules. The main components of the NPC are nucleoporins. About 30 different human Nups have been identified and appear to serve non-redundant functions. Nup210 is a membrane-spanning glycoprotein and major component of the NPC. It is essential for nuclear envelope structure and cell viability. Autoantibodies to Nup210 have been observed in patients with primary biliary cirrhosis (PBC), an autoimmune liver disease.