Expression systems for production of heterologous proteins

With the advent of our ability to clone and express a foreign gene in the heterologous host, came a remarkable capability to make almost any protein in abundant quantity to be used as therapeutic or diagnostic agents. It quickly led to the realization that proteins made in different hosts are different in many ways, particularly in their post-translation modifications. In this review a variety of available expression host systems are evaluated for heterologous production of proteins. Factors affecting the stability and expression of heterologous genes are also discussed. Eventual objective of producing a desired protein in an economical heterologous host is influenced by a variety of factors discussed in this review. Subsequent to the production, stabilization and formulation of proteins will pose significant hurdles in utilizing the natural biological catalysts and other proteins for therapeutic and industrial purposes.