Changes in glycosylation of rubella virus envelope proteins during maturation

Tunicamycin treatment of radioactively labelled infected Vero cells followed by electrophoresis in polyacrylamide gels showed that the mol. wt. of the putative polypeptide backbones of GP59(E1) and GP43(E2), the intracellular counterparts to the envelope proteins E1 and E2 of rubella virus, were 53000 and 34000, respectively. Two possible intermediates in the glycosylation of GP43(E2) were also identified. [3H]Mannose-labelled E1, E2, GP59(E1) and GP43(E2) were digested with Pronase and the glycopeptides separated by gel filtration. GP59(E1) contained glycopeptides in two size classes, designated R1.5 and R2.1; E1 contained these and an additional size class, R2.7. GP43(E2) contained glycopeptides in three size classes, R1.5, R2.1 and R2.7; E2 contained these and size class R3.3. The glycopeptides derived from GP59(E1) and GP43(E2) were all sensitive to endoglycosidase H treatment whereas the glycopeptides of E1 and E2 contained both sensitive and resistant components.