Fusion partners as a tool for the expression of difficult proteins in mammalian cells.

The expression of proteins which do not express well on their own can be enhanced by linking them to human serum albumin (HSA) or antibody crystallizable fragment (Fc). The constructs shown here are designed to secrete the proteins after transient transfection of mammalian cell lines. The fusion partners are appended to the N-terminus of the proteins and contain a linker designed to be proteolytically cleaved. Transient transfection and purification protocols are provided as well as experimental results with five interleukins.