Vesicular stomatitis virus glycoprotein is anchored to intracellular membranes near its carboxyl end and is proteolytically cleaved at its amino terminus

Abstract

The intracellular [Chinese hamster ovary cell] vesicular stomatitis virus glycoprotein (G) is inserted into membranes such that a small portion of 1 end of the molecule is exposed on the cytoplasmic surface of the endoplasmic reticulum and is susceptible to proteolytic digestion. This region of the G protein contains 2 methionyl tryptic peptides. The methionyl tryptic peptides of the G protein were ordered by the use of the antibiotic pactamycin, and the 2 methionyl tryptic peptides removed by proteolytic digestion of intracellular G protein were shown to derive from the carboxyl terminal end of the protein. The unglycosylated G protein synthesized in a reticulocyte cell-free reaction migrates on polyacrylamide gels slightly slower than the unglycosylated G protein synthesized in tunicamycin-treated infected cells. G proteins derived from different sources were compared by partial proteolysis and by chymotryptic peptide analysis. There were minor differences between the 2 proteins consistent with the removal of 10-15 amino acids from the amino terminus of the intracellular G protein.