ABSTRACT
In this chapter, the author describes recent studies on heterologous protein production with S cerevisiae and a few non-Saccharomyces yeast hosts, with particular reference to studies that might potentially provide improvement in the yield and quality of heterologous proteins produced in these hosts. He also briefly describes heterologous protein production by non-Saccharomyces yeast hosts. Taken together, all of the observations indicate that the yield of heterologous protein production in the S. cerevisiae host could be increased by using a host strain with nuclear mutations or with cytoplasmic mutation causing respiratory deficiency. Among the mutations particular interest is given to mnn9, ochl, ochl, algl, and algl because mutants with these mutations somehow display a deficiency in mannose outer-chain elongation of asparagine-linked oligosaccharide. If the yield of heterologous protein is unsatisfactory, it would be valuable to consider the possibility of proteolytic degradation of the proteins expressed.
