Mammalian recombinant proteins: vectors and expression systems.

Abstract

The determination of the biological properties and physiological significance of proteins is often hampered by the low level at which their genes are naturally expresSed. The therapeutic use of mammalian proteins is also limited by the availability of authentic material. A number of expression systems are now available for the high level production of mammalian proteins and, in some cases, these have been used to generate material of therapeutic use. Proteins such as human growth hormone, insulin, erythropoietin, tissue plasminogen activator, interleukin (IL)-2 and the interferons (IFNs) are examples of human therapeutic agents produced using heterologous expression systems. Although efficient expression can be achieved in many cases, there is a continued need for the improvement and refinement of expression systems to allow for the rapid production of authentic recombinant proteins including those that are lethal to host cells. To that end, a variety of expression systems have been devised and modified, each with distinct advantages and disadvantages. In order to be certain of producing bioactive proteins, it is essential that these alternative approaches are tried, as no one system can fi.tlfil all the requirements for successful production of mammalian proteins. In this review, I will summarize the main advances in the past year or two in the development of expression systems for mammalian recombinant proteins.