How to select an appropriate host cell?

The main reason recombinant proteins often fail to fold correctly in the E. coli cytoplasm is the reducing environment, which disfavors disulfide bond formation. To address this, researchers have mutated genes of key enzymes in the main reducing pathways for intracellular expression. This has led to the construction of competent cells that favor disulfide bond formation and correct protein folding, such as Origami(DE3), Origami B(DE3), Rosetta-gami(DE3), Shuffle, etc.