Secretory expression of porcine insulin precursor in methylotrophic yeast Pichia pastoris

Abstract

The methylotrophic yeast Pichia pastoris is a recently developed host for heterologous protein expression. As nonconventional yeast, it has the following advantages over S. cerevesiae: readiness of high-density growth and scaling-up, and the presence of a powerful methanol-regulated promoter AOXl (expressing AOX to 30% of total cell protein) [ 1]. Furthermore, the transformed strains with integrative expression are stable over generations. This system has been used in the expression of many heterologous proteins. We have already expressed insulin precursor in S. cerevisiae [2] and K. Iactis [3]. In order to increase the expression level, we have tried to express it in this system.