Replacement of the cytoplasmic dor glycoprotein in polarized cells

The envelope glycoprotein (G protein) of vesicular stomatitis virus (VSV) is transported to the basolat- eral plasma membrane of polarized epithelial cells, whereas the hemagglutinin glycoprotein (HA protein) of influenza virus is transported to the apical plasma membrane. To determine if the cytoplasmic domain of VSV G protein might be important in directing G protein to the basolateral membrane, we derived polarized Madin-Darby canine kidney cell lines expressing G protein or G protein with its normal cytoplasmic domain replaced with the cytoplasmic domain from an' influenza HA protein (GHA protein). Indirect immunofluorescence micros- copy showed that G protein was present primarily on basolat- eral surfaces, whereas the GHA protein was present on the apical and basolateral membranes. These results suggest that the cytoplasmic domain can be an important determinant directing polarized expression of an integral membrane pro- tein.