Two small virus-specific polypeptides are produced during infection with Sindbis virus

Publisher Website
Google Scholar
Abstract
Two small virus-specific polypeptides which are produced during infection of cells with Sindbis virus but which are not incorporated into the mature virion were identified and characterized. The larger is a glycoprotein with an approximate MW of 9800 and is found predominantly in the medium of infected cells. Three independent lines of evidence demonstrate conclusively that this 9800-dalton glycoprotein is produced during the proteolytic conversion of the precursor polypeptide PE2 to the virion glycoprotein E2. This small glycoprotein is therefore analogous to the virion glycoprotein E3 of the very closely related alphavirus, Semliki Forest virus. The 9800-dalton glycoprotein of Sindbis virus, unlike the E3 glycoprotein of Semliki Forest virus, is not present in the viral particle. The other virus-specific polypeptide is 4200 daltons, does not appear to be a glycoprotein and is not incorporated into the mature virus or released into the culture medium. The gene for this small polypeptide is present in the viral 26S mRNA (the mRNA which encodes all the viral structural polypeptides) and appears to be located in the portion of the mRNA which encodes the 2 viral glycoproteins. The possibility that this 4200 dalton polypeptide functions as a signal peptide during the synthesis of the viral membrane glycoproteins is discussed.