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 site 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 is 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.

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 a DNA sequence operably encoding IGF-1, in operational association with a DNA sequence encoding the S. cerevisiae alpha mating factor pre-pro sequence (including the proteolytic processing site: lys-arg), both under the regulation of a promoter region of a gene of a methylotrophic yeast, under conditions allowing expression of said DNA sequences, and secretion of IGF-1 into the culture medium.Also disclosed are novel DNA fragments and novel recombinant yeast strains which are useful in the practice of the present invention.

Abstract: Method for the recovery and purification of intact, correctly-folded, monomeric insulin-like growth factor-1 peptide from large volumes of IGF-1-containing medium are described, comprising a series of adsorption-desorption steps employing a combination of cation exchange and hydrophobic interaction adsorbents. Product IGF-1 peptide is highly purified and suitable for use in a variety of clinical applications.