The N-Terminus of PE2 in Sindbis Virus-Infected Cells

One of the two envelope glycoproteins of Sindbis virus, E2, and its intracellular precursor PE2 were obtained in chemically pure form from Sindbis infected cells by immunoabsorption with antibody against E2. The N-terminus of PE2, which is probably the signal sequence of this protein, was examined and two N-termini were found. One, the primary product of translation, was sequenced by Edman degradation and the other was found to be blocked and produced by N-acetylation of the first. It was also found that an asparagine residue at position 14 of PE2 is glycosylated. The putative signal sequence is not cleaved by signal peptidase either under normal conditions or when glycosylation is prevented with tunicamycin.