Shedding of the glycoprotein from vesicular stomatitis virus-infected cells

Abstract

In a culture of Chinese hamster ovary cells infected with vesicular stomatitis virus, there is specific shedding of viral antigens into the medium. This shedding appears to be unrelated to progeny formation or to cell lysis. Although all 5 of the virus-specific proteins are detected in the extracellular soluble fraction, the major antigen is the Gs protein. This protein has a MW of 54,000. Indirect analysis of the content of sialic acid as well as peptide analysis of the Gs and G proteins of vesicular stomatitis virus suggest that the Gs protein is derived from the G protein by proteolysis. Both proteins are hydrophobic when analyzed by charge-shift electrophoresis. The presence of phenylmethylsulfonyl fluoride in the culture medium or the removal of serum from the culture medium partially reduces the shedding of Gs protein. Increased shedding of the Gs protein is seen when there is an unstable M or matrix protein synthesized by a temperature-sensitive mutant, tsG31. The G protein is probably cleaved at the cell surface, thus releasing Gs protein into the medium. The stability of G protein at the cell surface appears to depend on its association with the M protein.