All Photos(5)



OverExpress C43(DE3) Chemically Competent Cells

for the highest protein expression



for molecular biology

cell transformation

competent cell type: chemically competent
transformation efficiency: ≥1 x 106 cfu/μg

shipped in

dry ice

storage temp.


General description

OverExpress Electrocompetent and Chemically Competent Cells are E. coli strains that are effective in expressing toxic proteins from all classes of organisms, including eubacteria, yeasts, plants, viruses, and mammals. The effectiveness of these new strains in expressing toxic proteins has been validated in more than 350 publications. The OverExpress strains contain genetic mutations phenotypically selected for conferring tolerance to toxic proteins. The strain C41(DE3) was derived from BL21(DE3). This strain has at least one mutation, which prevents cell death associated with expression of many recombinant toxic proteins. The strain C43(DE3) was derived from C41(DE3) by selecting for resistance to a different toxic protein and can express a different set of toxic proteins to C41(DE3). OverExpress C41(DE3)pLysS and C43(DE3)pLysS also carry a chloramphenicol-resistant plasmid that encodes T7 lysozyme, which is a natural inhibitor of T7 RNA polymerase. Cells containing pLysS produce a small amount of T7 lysozyme. These strains are used to suppress basal expression of T7 RNA polymerase prior to induction, thus stabilizing recombinants encoding particularly toxic proteins.


F – ompT hsdSB (rB- mB-) gal dcm (DE3)


OverExpress C43(DE3) Chemically Competent Cells have been used for transforming the toll/interleukin receptor (TIR) domain constructs of sterile alpha and TIR motif–containing protein 1 (SARM1).

Features and Benefits

  • Express genes cloned into any T7 vector with these BL21(DE3) derivatives
  • Effective in expressing toxic & membrane proteins
  • Cited in over 350 research articles


  • OverExpress C43(DE3) chemically competent cells
  • pUC 19 transformation control DNA
  • recovery medium for expression

Legal Information

OverExpress is a trademark of Imaxio, S.A.

Storage Class Code

12 - Non Combustible Liquids

Certificate of Analysis

Certificate of Origin

A Rangunwala et al.
Epidemiology and infection, 142(10), 2147-2154 (2013-12-18)
Crimean-Congo haemorrhagic fever virus (CCHFV) has the propensity to cause nosocomial infections with a high fatality rate. Handling the virus requires biosafety level-4 facilities, limiting accessibility for many laboratories. Advances in molecular techniques have allowed preparation of safe recombinant antigens...
Heather S Loring et al.
Bioorganic & medicinal chemistry, 28(18), 115644-115644 (2020-08-24)
Sterile Alpha and Toll Interleukin Receptor Motif-containing protein 1 (SARM1) is a key therapeutic target for diseases that exhibit Wallerian-like degeneration; Wallerian degeneration is characterized by degeneration of the axon distal to the site of injury. These diseases include traumatic...
Arthur Laganowsky et al.
Nature, 510(7503), 172-175 (2014-06-06)
Previous studies have established that the folding, structure and function of membrane proteins are influenced by their lipid environments and that lipids can bind to specific sites, for example, in potassium channels. Fundamental questions remain however regarding the extent of...


OverExpress™ Chemically Competent Cells

Protocol for OverExpress™ Chemically Competent Cells. Product Numbers: CMC0017, CMC0018, CMC0019, CMC0020, CMC0023, CMC0024

Our team of scientists has experience in all areas of research including Life Science, Material Science, Chemical Synthesis, Chromatography, Analytical and many others.

Contact Technical Service