Expression of genes encoding vesicular stomatitis and Sindbis virus glycoproteins in yeast leads to formation of disulfide-linked oligomers.

Saccharomyces cerevisiae strains transformed with plasmids containing cDNAs coding for the glycoproteins of vesicular stomatitis or Sindbis viruses can be induced to produce large amounts of glycosylated virus glycoproteins. Studies reported here show that these proteins from high molecular weight disulfide-linked oligomers in the yeast endoplasmic reticulum. Oligomers were also found for two genetically altered forms of VSV G; one of these was lacking the membrane anchor domain and the other had the cysteine in the cytoplasmic tail replaced with serine. These oligomers can be separated from the bulk of yeast proteins by brief high-speed centrifugation of yeast extracts prepared by boiling cells with 1% sodium dodecyl sulfate. Treatment with thiol-reducing agents converts the oligomers to soluble monomeric forms, and this procedure leads to a substantial purification of glycoproteins from bulk yeast protein.