Expression of a biologically active analogue of somatomedin-C/insulin-like growth factor I.
A synthetic gene coding for an analogue of somatomedin-C/insulin-like growth factor I (Sm-C/IGF-I) was synthesized by solid support phosphoramidite chemistry and subsequently cloned and expressed in Escherichia coli as a fusion protein. The gene, designed with a threonine codon substituted for a methionine codon at position 59 was expressed fused to an eight-amino acid leader peptide under the direction of the E. coli tryptophan promoter. The fusion protein, termed L0-[Thr59]-Sm-C/IGF-I was purified extensively (greater than 97%) and found to be 60% as active as native Sm-C/IGF-I in a radioimmunoassay and 50% as potent as native Sm-C/IGF-I in a radioreceptor assay. Like native Sm-C/IGF-I it was also mitogenic for Balb/c 3T3 cells. After removal of the eight amino acid leader peptide by cyanogen bromide treatment, the resulting threonine analogue, termed [Thr59]-Sm-C/IGF-I was 80% as potent as native Sm-C/IGF-I in both the RIA and the radioreceptor assays. It was also mitogenic in Balb/c 3T3 cells. These two analogues, therefore, display biological activities similar to human-derived Sm-C/IGF-I.
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D003001:Cloning, Molecular; D004274:DNA, Recombinant; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D007328:Insulin / Q000096:biosynthesis / Q000235:genetics* / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I; D051379:Mice; D008934:Mitogens; D009876:Operon; D010452:Peptide Biosynthesis; D010455:Peptides / Q000235:genetics* / Q000494:pharmacology; D010957:Plasmids; D013002:Somatomedins / Q000096:biosynthesis / Q000235:genetics* / Q000494:pharmacology
D004274:DNA, Recombinant; D007328:Insulin; D008934:Mitogens; D010455:Peptides; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I