| 摘要 |
In order to produce relatively large quantities of recombinant polypeptides having good ovine growth hormone activity which can be used in vivo as effective substitutes for the natural hormone, a complementary DNA (cDNA) sequence coding for a recombinant polypeptide having ovine growth hormone activity is provided together with a suitable cloning vector, so that the DNA sequence and cloning vector are ligated to deploy the DNA sequence into the cloning vector to form a molecular clone. The vector so formed may include a complete or partial copy of the ovine growth hormone polypeptide coding region, encompassing the mature hormone, extending past the 3 min termination codon. The DNA sequence coding may be derived from polyadenylated messenger RNA (mRNA) isolated from ovine pituitary glands by treating the mRNA with reverse transcriptase in the presence of oligodT primer to synthesize first strand complementary DNA (cDNA), enzymatically removing the mRNA with RNase H, and subsequently synthesising the second cDNA strand with DNA polymerase I, and treating the double stranded complementary DNA (cDNA) so formed with T4 DNA polymerase to create flush (blunt) ended molecules. |
