| abstract |
Insulin-like growth factor-1 (IGF-1), a naturally occurring, relatively short, single chain polypeptide, is prepared by growing methylotrophic yeast transformants containing in their genome at least one copy of DNA encoding IGF-1, in operational linkage with DNA encoding a signal sequence, which is effective for directing secretion of proteins from the host cells and which also includes the proteolytic processing syte lys-arg and may include one or more glu-ala sequences. In preferred embodiments the signal sequence is the S. cerevisiae alpha mating factor pre-pro sequence. Expression of both the DNA encoding IGF-1 and the pre-pro signal sequence are regulated by a promoter region derived from a methanol responsive gene of a methylotrophic yeast. DNA constructs and recombinant methylotrophic yeast strains used for the expression and secretion of IGF-1 are also provided. For preferred embodiments, protease deficient Pichia pastoris strains are provided. |