Expression of Cloned Genes in Using IPTG-Inducible Promoters.

Many expression vectors make use of the operon. In general, the operator () is located downstream from the promoter of the target gene, so that binding of the repressor blocks transcription initiation until lactose or the isopropyl-β-d-thiogalactopyranoside (IPTG) analog is added. The protocol given here is intended for use with IPTG-inducible vectors. l-Arabinose-inducible systems derived from the operon offer an alternative to expression systems based on the operon; guidance for their use is also provided.