Abstract: A new expression vector for the production of a polypeptide in yeast. The vector includes a sequence coding for the polypeptide and other sequences allowing expression of the polypeptide only in yeast. The other sequences lack any non-yeast sequences. Other embodiments include a yeast strain comprising such a vector, a method for the production of the vector, a method for the production of the yeast strain by transformation of a yeast strain with the new vector, and a method for the production of a polypeptide in the transformed yeast strain by fermentation thereof followed by isolation of the polypeptide.