Unknown. Cellular response protein to viral infection. Interacts with DYM. Early Golgi. Cycles via the cell surface and endosomes upon lumenal pH disruption. Widely expressed. Highly expressed in colon, prostate, trachea and stomach. Expressed at lower level in testis, muscle, lymphoid tissues, white blood cells and spleen. Predominantly expressed by cells of the epithelial lineage. Expressed at low level in normal liver. Expression significantly increases in virus (HBV, HCV) infected liver. Expression does not increase in liver disease due to non-viral causes (alcohol-induced liver disease, autoimmune hepatitis). Increased expression in hepatocytes appears to be a general feature of advanced liver disease. In liver tissue from patients with adult giant-cell hepatitis (GCH), it is strongly expressed in hepatocytes-derived syncytial giant cells. Constitutively expressed by biliary epithelial cells but not by hepatocytes. Up-regulated in response to viral infection. Induced by the E1A adenoviral protein. Glycosylated. Phosphorylation sites are present in the extracellular medium. Belongs to the GOLM family. It is uncertain whether Met-1 or Met-2 is the initiator.