Translation of mammalian mRNAs in cell-free extracts of ascites cells and wheat germ.

Translation constitutes an important and reliable means, though not the only means, for the identification and assay of mRNAs. The value of well-characterized systems capable of translating a variety of heterologous mRNAs has become increasingly apparent over the last 3-4 years. Currently systems of several sorts are available, ranging from highly fractionated cell-free extracts to the unrefined reticulocyte lysate and intact Xenopus oocytes. In the present article, we review some properties and applications of systems of an intermediate level of complexity. These systems, preincubated S-30 extracts (post-mitochondrial supernatants) of eucaryotic cells, offer the advantage of a low endogenous background together with the convenience of relatively simple preparation and use. In this regard they resemble the analogous extracts of bacterial cells which have played a major role in investigations of the metabolism of procaryotic mRNAs. These principles are illustrated by reference to S-30 extracts of Krebs I1 ascites cells and of wheat germ.