Expression and secretion of bovine beta-lactoglobulin in Saccharomyces cerevisiae.

A bovine beta-lactoglobulin (beta-LG) was expressed in Saccharomyces cerevisiae carrying bovine pre-beta-LG cDNA and secreted into its growth medium. The expression plasmid was constructed by inserting the whole coding region of the cDNA encoding pre-beta-LG between the promoter and terminator of the yeast glyceraldehyde 3-phosphate dehydrogenase gene of pYG100, a yeast expression vector. In the supernatant of the yeast growth medium, beta-LG with a native conformation was detected by sandwich ELISA, and its amount was estimated to be 1.1 mg/l. A Western-immunoblotting analysis revealed that beta-LG secrected in the growth medium had the same mobility as that of authentic bovine beta-LG. The N-terminal sequence was also identical with that of authentic mature bovine beta-LG.