[Studies on the expression of the recombinant human GM-CSF/IL-3 fusion protein].

A human granulocyte-macrophage colony stimulating factor (GM-CSF)/interleukin-3(IL-3) fusion gene with a short linker between the GM-CSF and IL-3 gene has been successfully constructed and expressed in E. coli under the control of T7 promoter. The recombinant fusion protein was expressed as inclusion bodies after the IPTG induction. The yield of the GM-CSF/IL-3 fusion protein was over 30% of the total cellular proteins. Western-blotting results showed that the fusion protein could specifically combined with GM-CSF antibody and IL-3 antibody. The biological activity was detected by the GM-CSF and IL-3 dependent cell line TF-1. After solubilizing with 8 mol/L urea and renaturing with dialysis against Tris. HCl solution, the refolded fusion protein showed obvious activities to maintain the growth of TF-1 cell.