[Soluble high-expression, purification and bioassay of IGFBP-3].

cDNA for Insulin-like growth factor binding protein 3 was cloned and constructed a prokaryotic expression vector--pET-DsBA-IGFBP3. The construct was transformed into E. coli BL21 (DE3)plysS. The induced fusion protein (D-IGFBP3) was expressed successfully in soluble form. We obtained D-IGFBP3 the purify of which is over 95% after purification by His affinity chromatography. The product was identified by Western-blot. The cell assay showed that the obtained fusion protein can inhibit the growth of MCF-7 and bind with IGF-I in vitro.