of human growth hormone hgh gene was cloned particularly the present inventors requested bioneer co daejeon korea to synthesize the human growth hormone gene ncbi reference nm u2014 000515 3 141 719 for the expression of the recombinant human growth hormone with the insertion of nhei restriction enzyme cleavage site gctagc at 5 u2032 end and xhoi restriction enzyme cleavage site ctcgag at 3 u2032 end seq id no 1 the synthesized cdna was ligated to pet 28a novagen madison wis usa by using the restriction enzymes nhei and xhoi leading to the construction of his hgh expression vector expressing the recombinant human growth hormone that contains 6 histidine tag and thrombin cleavage site at n terminal for the untagged hgh expression vector expressing the recombinant human growth hormone without histidine tag cdna containing ncoi restriction enzyme cleavage site ccatgg at 5 u2032 end and xhoi restriction enzyme cleavage site ctcgag at 3 u2032 end was constructed by pcr using the above synthesized cdna as a template with the forward primer 5 u2032 ccatggcgatgttcccaaccatt 3 u2032 seq id no 2 and the reverse primer 5 u2032 ctcgagctagaagccacagct 3 u2032 seq id no 3 the pcr product was digested with ncoi and xhoi and then ligated to ncoi and xhoi restriction enzyme sites of pet28a expression vector in order to express the untagged recombinant human growth hormone untagged hgh the nucleotide sequence of the gene for the expression was identified by automatic sequencing as a result vectors for the expression of each 6 histidine tag containing human growth hormone and 6 histidine tag.