The secretion of glucagon by transformed yeast strains.

Saccharomyces cerevisiae strains were transformed with plasmids coding for modified mating factor alpha 1 leader sequences followed by glucagon. Glucagon-containing peptides which were secreted into the fermentation broth were isolated and their amino acid sequences determined. The yeast strain transformed with the sequence coding for the complete mating factor alpha 1 leader sequence preceding the glucagon gene (MT556) secreted glucagon plus glucagon extended at its N-terminal by parts of the leader sequence. The yeast strain transformed with the sequence coding for a truncated mating factor alpha 1 leader sequence before the glucagon gene (MT615) secreted glucagon. These observations suggest that S. cerevisiae is a suitable vehicle for the efficient expression of plasmids coding for polypeptides similar to glucagon (e.g. VIP, secretin, GIP).