Overview of Bacterial and Yeast Systems for Protein Expression

Over the past decade the variety of hosts and vector systems for recombinant protein expression has increased dramatically. Researchers now select from among mammalian, insect, yeast, and prokaryotic hosts, and the number of vectors available for use in these organisms continues to grow. With the increased availability of cDNAs and protein coding sequencing information, it is certain that these and other, yet to be developed systems will be important in the future. Despite the development of eukaryotic systems, E. coli remains the most widely used host for recombinant protein expression. Optimization of recombinant protein expression in prokaryotic and eukaryotic host systems has been carried out by varying simple parameters such as expression vectors, host strains, media composition, and growth temperature. Recombinant gene expression in eukaryotic systems is often the only viable route to the large-scale production of authentic, post translationally modified proteins. It is becoming increasingly easy to find a suitable system to overexpress virtually any gene product, provided that it is properly engineered into an appropriate expression vector.