The technique of in vitro protein synthesis involves the translation of messenger RNA (mRNA) in a cell-free extract to yield polypeptide products. Both prokaryotic and eukaryotic systems have been developed, but for this experiment only a eukaryotic system will be considered. In 1973, Roberts and Paterson (3 ) demonstrated that a cell-free extract of wheat germ would faithfully translate rabbit globin mRNA and tobacco mosaic virus RNA to yield full-length polypeptide products. Other systems have also been developed, one of the most popular being the rabbit reticulocyte lysate developed by Pelham and Jackson (2 ) in 1976. Both wheat germ and reticulocyte lysates are used extensively, and both have advantages and disadvantages (Table 1 ), but the choice of system often depends on personal preference. For the experiment outlined in this chapter, the wheat germ lysate is used because it is easy to prepare and the starting material is readily available.
