Intracellular formation of two soluble glycoproteins in BHK cells infected with vesicular stomatitis virus serotype New Jersey.

Infection of BHK 21 cells with VSV serotype New Jersey gave rise to three intracellular viral glycoproteins: the membrane-integrated G protein and the two soluble glycoproteins Gs and Gss which lacked the cytoplasmic and transmembrane domains as was deduced from limited chemical cleavage of the glycoproteins by hydroxylamine. Both soluble glycoproteins were completely protected by the microsomal membrane against proteolytic digestion. The soluble glycoproteins were formed in the endoplasmic reticulum because both were fully endo H sensitive after a 5-min pulse with [35S]methionine. Protease inhibitors and lysosomorphic agents had no effect on the yield of Gs and Gss. Tunicamycin treatment of VSV-infected cells reduced extensively viral particle maturation without affecting significantly the release of Gs and Gss. Two other glycosylation inhibitors, swainsonine and deoxynojirimycin did not decrease virus particle formation and secretion of both soluble glycoproteins. Since the glycosylation inhibitors showed a differential effect on the processing and transport of the glycoproteins a precursor-product relationship between G protein and soluble glycoproteins is highly unlikely. Both soluble glycoproteins were also synthesized in vitro in a reticulocyte lysate without microsomal membranes when primed with RNA extracted from VSV-infected cells or with newly transcribed mRNA from nucleocapsids in a coupled transcription system. Thus, proteases localized in the lumen of the ER seemed to be not essential for the generation of both soluble glycoproteins.