"We have investigated the over-production of seven membrane proteins in Council Laboratory of an Escherichia coli–bacteriophage T7 RNA polymerase expression system. Molecular Biology In all seven cases, when expression of the target membrane protein was Hills Road, Cambridge induced, most of the BL21(DE3) host cells died. Similar effects were also CB2 2QH, UK observed with expression vectors for ten globular proteins. Therefore, protein over-production in this expression system is either limited or prevented by bacterial cell death. From the few survivors of BL21(DE3) expressing the oxoglutarate-malate carrier protein from mitochondrial membranes, a mutant host C41(DE3) was selected that grew to high saturation cell density, and produced the protein as inclusion bodies at an elevated level without toxic effect."
Science Over-production of Proteins in Escherichia coli: Mutant Hosts that Allow Synthesis of some Membrane Proteins and Globular Proteins at High Levels (.pdf):