Mechanism of premature polypetide termination in a mouse ascites cell-free system programmed by encephalomyocarditis viral RNA.

The premature termination and release of encephalomyocarditis viral RNA-programmed polypeptides were analyzed in a cell-free system from mouse ascites tumor cells. The KCL concentration affects the size distribution of products but not the extent of polypeptide release. The same major products (60,000 to 140,000 molecular weight) are found in both the soluble and particulate fractions. The majority of released polypeptides are free protein, whereas the ribosome-bound product is mostly in the form of peptidyl-tRNA.