Comparison of wild and mutant β-lactoglobulin production between mammalian cells and yeast

Abstract

The β-lactoglobulin (β-LG) mutant, W19Y, in which residue 19 of tryptophane is replaced with tyrosine, was produced in both yeast and mammalian COS-7 cell. The amount of secreted W19Y in the yeast was 6-fold greater than that of wild β-LG, while W19Y and wild β-LG secreted into supernatants of the COS-7 cells were almost equal. The slightly perturbed conformation and the greatly reduced molecular stability of W19Y may have resulted in an increased transnational efficiency in yeast. In contrast, in COS-7 cells, this increased molecular flexibility of W19Y did not promote the secretion, but rather enhanced the unfolding of W19Y in the culture supernatant of COS-7.