Yeast protein expression systems are faster, more convenient, and less expensive to grow than mammalian systems. They also provide a high level of protein expression (10-100 fold) as compared to E. coli. These systems also allow for the synthesis of both complex and multi-subunit proteins. Additionally, protein can be expressed as a secretory protein, which assists in the processing and purification of the gene product. Another advantage is that it is capable of post-translational protein modification and processing. It also provides high-density fermentation, which is suitable for industrial use.