Method for the production of insulin-like growth factor-1

1. A method for the production of IGF-I, said method comprising:

a) cultivating a prokaryotic host cell comprising an expression vector containing a nucleic acid encoding a fusion protein comprising said IGF-I N-terminally linked to the C-terminus of a propeptide, whereby said propeptide ends C-terminally with amino acids -Y-Pro, wherein Y is selected from the group consisting of Pro, Pro-Ala, Arg-Pro, and Pro-Arg-Pro, and

b) recovering and cleaving said fusion protein with IgA protease to recover said IGF-I.

2. The method of claim 1 , wherein said IGF-I is selected from the group consisting of: IGF-I (SEQ ID NO:1), an IGF-I SEQ ID NO: 1, in which at the C-terminus 3-6 amino acids are deleted, IGF-I of SEQ ID NO. 1, in which at amino acid position 36 arginine is substituted by alanine, and IGF-I of SEQ ID NO. 1 , in which at amino acid position 37 arginine is substituted by alanine.

3. The method of claim 1 , wherein said IGF-I is C-terminally linked to human Fc from IgG.

4. The method of claim 1 , wherein said propeptide has the following amino acid sequence:

Met-X 1 -His n -X 2 -Y-Pro-, wherein

Met denotes methionine,

X 1 is a bond, serine or asparagine,

His is histidine,

n is a number from 0 to 6,

X 2 is a linker peptide, selected from the group consisting of peptides SEQ ID NO: 6-10,

Pro is proline, and

Y is selected from the group consisting of Pro, Pro-Ala, Arg-Pro, and Pro-Arg-Pro.