Translation of Semliki-Forest-Virus 42-S RNA in a Mouse Cell-Free System to give Virus-Coat Proteins.

Semliki-Forest-virus 42-S virion RNA is translated in a mouse ascites cell-free system. One of the major polypeptides made in vitro has been identified as Semliki-Forest-virus capsid protein by co-electrophoresis on dodecylsulfate -- polyacrylamide gels and by tryptic peptide analysis on paper. Another major product of the cell-free system has been characterised as envelope protein by peptide analysis but it does not co-electrophorese on gels with envelope proteins from purified virions. It is possible that the nascent, non-glycosylated polypeptide is partially degraded by proleolytic enzymes present in the cell-free extract, or alternatively that fragments of envelope protein are produced by premature termination on the viral RNA. Several other polypeptides are synthesised in the cell-free system in variable amounts but these have not been identified. The genetic content and the mechanism of translation of Semliki-Forest-virus 42-S RNA are discussed. [ABSTRACT FROM AUTHOR]