The PEF offers protein expression services focused on three recombinant expression systems, which collectively will enable production of a broad range of target proteins suitable for a wide variety of downstream applications. These are E.coli, mammalian cell expression, and insect cell expression. In each case, the PEF offers small scale test expression, expression optimisation, and large scale expression.
E.coli: A widely used expression system, E.coli production is quick, highly manipulable, low-cost in terms of reagents, and capable of generating high expression of the protein of interest. In addition, a diverse range of expression vectors and affinity tags/fusion partners are available, and efficient 2-H, 13-C, 15-N and Selenomethionine labeling approaches are established for downstream NMR and X-ray crystallographic applications. Limitations of E.coli expression systems include lack of post-translational modifications, and absence of suitable chaperones necessary for folding of some eukaryotic proteins.
Mammalian 293T: Recombinant expression in the Human Embryonic Kidney (HEK) 293T variant cell line is a widely used, quick and relatively cheap approach that is capable of generating high levels of a wide range of eukaryotic target proteins. Advantages include incorporation of human post-translational modifications, availability of glycosylation mutant strains, and the fact Selenomethionine labeling strategies for X-ray crystallographic approaches are established in this system. In addition, 293T expression is widely used for generation of immunogens for antibody production.
Insect: Stable transfection of Drosophila S2 cells is a well-established system for recombinant production of a wide range of proteins, including oligomeric complexes and cell surface proteins, and allows good expression levels and relatively homogenous glycosylation. One limitation is the length of time (~4 weeks) for selection of stable expression clones.