Recombinant overexpression of a protein or a protein complex using any specific heterologous host can be an overwhelming challenge. The reasons may range from low yield and poor solubility of a single-subunit enzyme to the wrong stoichiometry or the incomplete assembly of a multiprotein complex. Whatever the reason, overcoming the difficulties will take the researcher into a journey through the seemingly countless options that exist for protein expression. While some choices stand to reason fairly straightforwardly (e.g., using Escherichia coli for the production of bacterial enzymes), most other choices do not need to be so self-revealing. Here, we attempt to portrait the canvas of available hosts for heterologous expression of many different protein classes and complexes and offer guidance as to which expression host may be more suitable to the problem at hand. The guidance in this chapter must be taken only as a rough indication which will have to be checked against the available literature and corroborated by experiment. It is not only expected but also welcome that, as more knowledge is gathered about the performance of hosts and protein types and new expression systems develop, the information in this chapter will have to be updated and refined.
Keywords: Baculovirus; E. coli; Expression host; Heterologous expression; Mammalian culture; Protein complex; Yeast.