Improved Secretion of Native Human Insulin-Like Growth Factor 1 from gas1 Mutant Saccharomyces cerevisiae Cells

ABSTRACT We studied the secretion of recombinant human insulin-like growth factor 1 (rhIGF-1) from transformed yeast cells. The hIGF-1gene was fused to the mating factor α prepro- leader sequence under the control of the constitutive ACT1 promoter. We found that the inactivation of the GAS1 gene in the host strain led to a supersecretory phenotype yielding a considerable increase, from 8 to 55 mg/liter, in rhIGF-1 production.