Expression of MUC1 in Insect Cells Using Recombinant Baculovirus

MUC1 mucin undergoes multistep posttranslational modifications before it is finally expressed on the apical surface of mammalian ductal epithelial cells. Two early precursor proteins are both N-glycosylated and differ in molecular weight owing to a proteolytic cleavage of a 20-kDa fragment. Proteolytically modified form is transported to the Golgi, where it undergoes extensive, although not complete, O-gly-cosylation on serine and threonine residues within the tandem repeat (TR) region. MUC1 is then transported to the cell surface. For additional glycosylation and sialylation, surface MUC1 is internalized and directed to trans-Golgi compartments. Mature form is again transported to the cell surface (1).