Advances in protein technologies have mushroomed to meet the growing demand for purified proteins for biomedical studies, structural genomics endeavours and clinical trials. The choice of an expression system is driven by a number of considerations, including the post-translational modifications that the product requires, whether a soluble protein is desired and whether the polypeptide is to be secreted. Often, however, the choice of an expression system is based on in-house expertise and familiarity with a subset of expression system. In this book internationally renown authors comprehensively review current and emerging expression technologies. Detailed reviews of the molecular genetics of expression systems in various organisms are presented. Topics covered include: Expression of extremphilic proteins; expression in E. coli, Bacillus spp., Saccharmyces cerevisiae, and methylotrophic yeasts; insect cell expression and the baculovirus system; and Chinese Hamster Ovary (CHO) cell lines for large-scale protein production. Also covered are two emerging expression systems, Methylobacterium extorquens AM1 and Caulobacter crescentus.