Efficient usage of a galactose-inducible expression vector for the production of heterologous protein in yeast.

We found that the expression vector previously constructed using the promoter of the GAL7 gene of Saccharomyces cerevisiae lacked the transcription terminator. The addition of the GAL7 terminator resulted in a more than 3-fold increase in the production of the protein encoded by cDNA of early region la (Ela) of human adenovirus, without affecting the amount of its mRNA. The positive regulatory gene, GAL4, when amplified with a vector of a high copy number, caused an about 5-fold increase in Ela production. We also found that medium containing a mixture of galactose and glucose can be used for the efficient production of the Ela protein.