Comparison of three different cell-free systems for turnip yellow mosaic virus RNA translation

The two proteins of molecular weights 150,000 and 195,000 specific of turnip yellow mosaic virus (TYMV) RNA translation in reticulocyte lysates have now also been detected in two other cell-free systems programmed with TYMV RNA: the wheat germ extract and the Ehrlich ascites cell-free system. The wheat germ extract contains proteases that affect the nascent TYMV polypeptide chains. The specific post-translational maturation of the protein of molecular weight 195,000 known to occur in the reticulocyte lysate has been investigated in the ascites system. An N-terminal fragment and a C-terminal fragment of molecular weights 120,000 and 78,000, respectively, could be detected co-migrating with the post-translational cleavage products observed in the reticulocyte lysate. Similarly, a C-terminally labelled 78,000 molecular weight fragment could be observed in the wheat germ system. The differences between the three in vitro systems with respect to TYMV RNA translation are discussed.