Introduction to the GS System™
The Gold Standard for Mammalian Gene Expression
Lonza’s powerful proprietary GS Gene Expression System™ uses a robust viral promoter and selection via glutamine metabolism to provide rapid development of high-yielding and stable mammalian cell lines. The GS System™ is successfully used by over 100 global pharmaceutical and biotechnology companies and is familiar to all authorities. Nineteen products have been approved which use the GS System™ including Zenapax® (Roche), Synagis® (Medimmune) and Solaris® (Alexion).
The international use of the GS System™ by both commercial organizations and academic institutions has led to a large body of published information.
Lonza has itself created hundreds of cell lines using the GS System™, many of which have been grown at large-scale and produced product for use in clinical trials and in-market supply. Other GS System™ users have accumulated experience with a diverse range of products where high yields have been achieved. Many investigators use the GS System™, not only to develop a manufacturing process, but as a tool to create recombinant proteins for biological studies. The reliability of the GS System™, as a consistent means of rapidly generating high-producing cell lines, will ultimately reduce your time to market.
Lonza can also offer you a full line of Cell Line Construction Services using our world-class GS System™ for mammalian protein production.
Download our GS Gene Expression System™ Brochure to learn more about Lonza’s proprietary expression technologies.
Principles of the GS Gene Expression System™
Glutamine synthetase (GS) is the enzyme responsible for the biosynthesis of glutamine from glutamate and ammonium. This enzymatic reaction is the pathway for glutamine formation in a mammalian cell.
In the absence of glutamine in the growth medium, the GS enzyme plays an essential role in the survival of mammalian cells in culture. Some mammalian cell lines, such as mouse myeloma lines, do not express sufficient GS to survive without added glutamine. With these cell lines, a transfected GS gene can function as a selectable marker by permitting growth in a glutamine-free medium. Other cell lines, such as Chinese hamster ovary (CHO) cell lines, express sufficient GS to survive without exogenous glutamine. In these cases, the GS inhibitor, methionine sulphoximine, can be used to inhibit endogenous GS activity such that only transfectants with additional GS activity can survive.