Process for making desired polypeptides in yeast

A process of making a desired polypeptide in yeast by culturing in a suitable culture medium a yeast strain containing an expression vector that expresses a sequence with the following formula

• SP-LP-Xn-PS-*polypeptide*
• wherein
• SP is a signal peptide;
• LP is the native α-factor leader peptide or a leader peptide being at least 85% identical to the native α-factor leader peptide;
• PS is a monobasic processing site Lys or Arg;
• X is a spacer peptide containing n amino acids;
• n is 0 or an integer from 1 to 10;
• and
• *polypeptide* is the desired polypeptide;
• with the proviso that the spacer peptide X is not Ile-Glu-Gly, Leu-Pro, Lys-Lys-Leu-Ile-Asp (SEQ ID NO:
• 4), Ile-Asp or Pro-Gly-Asp-Pro (SEQ ID NO:
• 5) and with the further proviso that the spacer peptide X does not contain a KEX2 cleavage site or together with PS or LP constitutes a KEX2 cleavage site and, when n=0, the C-terminal of the leader peptide is not Lys, Arg, Ile-Glu-Gly, Leu-Pro, Lys-Lys-Leu-Ile-Asp (SEQ ID NO:
• 4), Ile-Asp or Pro-Gly-Asp-Pro (SEQ ID NO:
• 5), whereupon the leader bound desired polypeptide is cleaved off at the processing site PS, either in vivo during passage through the cell membrane or in vitro after secretion into the culture medium whereupon the desired polypeptide is isolated.