ABSTRACT

Expression of several foreign genes in yeast has been achieved using autonomously replicating hybrid plasmids as described, however, it is also possible to place such expression systems into the yeast genome. Recombinant DNA research in yeast became possible in 1978 when Hinnen et al. demonstrated the first successful introduction (transformation) of foreign DNA into yeast. This initial procedure resulted in integration of the plasmid DNA into the yeast genome; however, similar procedures have also been used by Beggs, Struhl et al., and Hsiao and Carbon to obtain transformation with autonomously replicating yeast plasmids containing yeast 2 µm plasmid or chromosomal origins of replication. There are several possible advantages that yeast heterologous expression systems may have over E. coli systems. A slight disadvantage of yeast, as compared to E. coli or other bacterial host systems, is the difficulty of breaking the cells to obtain the product.