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Single-Use BL21(DE3)pLysS Competent Cells

by Promega
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  • Overview
  • Protocols
  • Specifications
  • Resources
  • BL21(DE3)pLysS Competent Cells allow high-efficiency protein expression of any gene that is under the control of a T7 promoter and has a ribosome binding site. BL21(DE3)pLysS is lysogenic for ?-DE3, which contains the T7 bacteriophage gene I, encoding T7 RNA polymerase under the control of the lac UV5 promoter. BL21(DE3)pLysS also contains a plasmid, pLysS, which carries the gene encoding T7 lysozyme. T7 lysozyme lowers the background expression level of target genes under the control of the T7 promoter but does not interfere with the level of expression achieved following induction by IPTG. For researchers performing more than one transformation, competent cells are available in standard format (200µl aliquots). For added convenience, single-use competent cells (50µl aliquots) also are available.

    Genotype: F–, ompT, hsdSB (rB–, mB–), dcm, gal, ?(DE3), pLysS, Cmr.


    1. Studier, F.W. and Moffatt, B.A. (1986) J. Mol. Biol. 189, 113–30.
    2. Davanloo, P. et al. (1984) Proc. Natl. Acad. Sci. USA 81, 2035–9.
    Inducible Protein Expression

    BL21(DE3) is an expression strain suitable for high level induction and expression of genes from any T7 promoter-based expression vector. T7 RNA polymerase expression is induced by the addition of 1mM IPTG to the culture.

  • Protocols

    Complete Protocol

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    E. coli Competent Cells Technical Bulletin

    PDF (686 KB)

    Quick Protocols

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    E Coli Competent Cells Quick Protocol FB035

    PDF (175 KB)

  • Certificate of Analysis

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    Storage Conditions

    LESS THAN -65C

    Use Restrictions

    For Research Use Only. Not for Use in Diagnostic Procedures.

  • Resources