Localization of two cellular forms of the vesicular stomatitis viral glycoprotein

Abstract

Two [Chinese hamster ovary, CHO] cell-associated forms of the glycoprotein (G) of vesicular stomatitis virus, termed G1 and G2, were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoesis. G1 has the higher electrophretic mobility, but both forms migrate more slowly than G protein synthesized in a wheat germ cell-free system (G0), which presumably is the unglycosylated form. G1 is a kinetic precursor of the G2 form, and the apparent cause of the electrophoretic difference between the 2 species in the presence of N-acetylneuraminic acid on the G2 form. Conversion of G1 to G2 occurs 10-20 min prior to the appearance of the G2 form of the protein on the cell surface. The G protein may be completely glycosylated several minutes prior to its migration to the cell surface, and glycosylation may not be the limiting step in its maturation. No glycoprotein comigrating with G0 can be detected in the infected cells, even after 5-min labeling periods; partial glycosylation of G probably occurs concomitantly with or immediately after its synthesis.