Wheat germ systems for cell‐free protein expression

Cell‐free protein expression plays an important role in biochemical research. However, only recent developments led to new methods to rapidly synthesize preparative amounts of protein that make cell‐free protein expression an attractive alternative to cell‐based methods. In particular the wheat germ system provides the highest translation efficiency among eukaryotic cell‐free protein expression approaches and has a very high success rate for the expression of soluble proteins of good quality. As an open in vitro method, the wheat germ system is a preferable choice for many applications in protein research including options for protein labeling and the expression of difficult‐to‐express proteins like membrane proteins and multiple protein complexes. Here I describe wheat germ cell‐free protein expression systems and give examples how they have been used in genome‐wide expression studies, preparation of labeled proteins for structural genomics and protein mass spectroscopy, automated protein synthesis, and screening of enzymatic activities. Future directions for the use of cell‐free expression methods are discussed.