| Insulin-like growth factors (IGFs) are consisted of two kinds of peptide, one is insulin-like growth factor I (IGF- I ) and another is insulin-like growth factor II (IGF-II). Many studies showed that IGFs play very important regulated roles in the cell proliferation and apoptosis, pathogenesis of human cancer and tissue differentiation.In order to get sufficient quantities of pure biologically active hIGFs to meet the need of basic research and clinical use, we cloned the gene of IGFs into pET plasmids, a series of prokaryotic expression vector, and expressed the recombinant plasmids in the E. coli of BL21.1. Genes of IGFs, which include CDS, were cloned by way of RT-PCR from the tissue of human placenta, then ligated the genes of IGFs to the vector of pMD18-T, the sequences of IGFs are correct by sequencing.2. Genes coding mature peptide of IGFs were achieved by PCR using another pair of oligo-nucleotide primers to induce to the suitable restriction enzyme site, and the IGF- I product of PCR contains 230 base pairs. IGF- II contains 219 base pairs.3. The genes of hIGF- I and hIGF- II were ligated into the expression vector pET-32a (+) and pET-30a (+) respectively after cut by the restriction enzymes, we introduced the recombinant vector pET-32a(+)-IGF- I and pET-30a(+)-IGF- II into the E. coli of BL21(DE3) after encoding fragment of recombinant vectors construct correctly which are confirmed by sequencing.4. SDS-PAGE analysis suggested that the bacteria containing the recombinant plasmid pET-32a (+)-IGF- I produced the fusion protein of 30kDa as it was induced by IPTG. consisting 10% of the total bacterial proteins, and the pET-30a (+)-IGF-II produced the fusion protein of 14kDa, which consisting 35% of total bacterial proteins.5. We find that the fusion proteins are inclusion bodies when the bacteria lysised by the lysozyme. The product of pET-32a(+)-IGF- I was analyzed by Western blotting, which confirmed that the hybrid protein was expressed as expected.
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