Target genes are often expressed in more than one system for various purposes. For example, a bacterial system may be used for initial studies to ascertain solubility or activity, or to produce large amounts of protein for structural studies or antibody production. The same gene may need to be expressed in insect and/or mammalian cells, to obtain higher activity or eukaryotic post-translational modifications. Although Novagen bacterial and baculovirus expression vectors offer compatible cloning strategies and restriction sites to make the cloning process more convenient, the entire process can be streamlined by using a single vector to reliably express target genes in the three major expression systems. The benefits of such a multisystem vector are enhanced when performing high-throughput (HT) gene analysis, which currently require a significant effort to construct and manage all of the multiple recombinants used for different expression systems.

To address this need, Novagen developed the pTriEx™ System, a novel expression vector platform that enables optimal protein expression in bacterial, insect, and mammalian cells from a single plasmid. 

The pTriEx™-7 vector is uniquely designed to allow rapid characterization of target genes in multiple expression systems. With this vector, a single recombinant plasmid can be used to test expression in E. coli, insect and mammalian cells. Transient mammalian expression is mediated by the CMV immediate early enhancer and promoter. For expression in insect cells, pTriEx-7 contains flanking baculovirus sequences to permit the generation of recombinant baculoviruses using the BacVector™ System or BacMagic™ Kits. In baculovirus-infected insect cells, expression is driven by the very late p10 promoter. Expression in E. coli is regulated by the tightly controlled T7lac promoter. For expression in E. coli, pTriEx recombinant plasmids can be transferred into a (DE3)pLacI host that allows IPTG based induction. The pTriEx-7 contains the coding sequence for the mouse IgM signal sequence to allow secretion of the expressed protein. pTriEx-7 also encodes an N-terminal 8 aa Strep•Tag ® II coding sequence followed by an enterokinase protease cleavage site and a multiple cloning site, with the option to include a C-terminal His•Tag ® coding sequence with 10 histidines. Additionally, the pTriEx-7 vector is available as an Ek/LIC Vector Kit.