1. Page 1 Protein expression system in Profacgen(1) by Profacgen

2. Page 2 Mammalian Cell Expression Mammalian cell expression systems are the best choice for the production of eukaryotic proteins, especially when correct folding and post-translational modification (glycosylation, phosphorylation, etc.) is required. They produce eukaryotic recombinant proteins in the most natural state, with native tertiary structure, physiochemical characteristics, and bioactivities. They have been successfully applied in the biopharmaceutical production of cytokines, monoclonal antibodies, growth factors and so on. The most widely-used mammalian cell lines are HEK293 and CHO cells.

3. Page 3 Cell-free protein expression Cell-free expression system produces proteins in vitro through translation machineries extracted from cells. It has become a well-developed technique for synthesizing proteins in cell lysates. This approach meets with the increasing demands for a more straightforward, rapid and efficient way of protein production. Cell-free expression overcomes many obstacles of conventional cellular expression. Firstly, it is ideal for high-throughput screening of mutagenesis. Moreover, the system works independently and is free of cellular context. The whole machinery sets up a better environment to manufacture toxic proteins, membrane proteins and proteins that would be easily degraded by intracellular proteases. In addition, the reaction steps can be simply manipulated by adding/removing certain factors, such as cofactors, energy sources, detergents and so on.

4. Page 4 Animal-free Expression Plant expression systems are used when animal-free recombinant protein products are required. Compared to traditional microbial or animal cell systems, the animal-free plant expression systems greatly reduce the risk of contamination with animal-origin pathogens. Furthermore, plant production possesses superior advantages in storage, distribution and scale-up. Many plant species have been developed as protein expression systems, such as rice, tobacco, and Arabidopsis thaliana. To obtain transgenic plants for the stable expression of proteins, plant virus and bacterium are utilized to deliver the desired gene into plant hosts. The most commonly used delivery systems include tobacco mosaic virus (TMV) and Agrobacterium.