Protein Expression with Stable S2 Cell Line
Many proteins go through post translational modifications (PTM) to mature with correct folding to be functional. These PTMs can only be achieved in mammalian, insect or, to some extent, in yeast cells. To purify small amount of proteins with PTM for activity assays, it is often done by transient transfection with mammalian cells.
It is, however, difficult to produce large amount of proteins for long term projects as mammalian cell transfection is of low efficiency and a good portion of transfected cells die due to toxicities from transfection reagent. Mammalian cell culture yield very little cells per unit of culture media and culture space, especilly for monolayer mammalian cell cutlure. Stringent requirements for mammalian cell culture, such as a CO2 incubator also add to the difficulties using mammalian cells to produce large quantities of recombinant protein with activities require PTMs.
Insect cells like drosophila S2 cell can over come many of the above difficulties to produce active proteins with PTMs: ultra high cell culture yield, low requirement for cell culture. Once a stable S2 cell line is made with your gene of interest (GOI), you can culture some cells easily in any laboratory for purification either from the culture media (secreted) or cell lysate.
