Cloning and expression of human growth hormone in E. coli system

The human growth hormone (hGH) stimulates growth, cell reproduction and regeneration in 
humans. Recombinant hGH (rhGH) is approved for the treatment of multiple human diseases 
resulting from hGH deficiency. This study aimed to produce a system for production of rhGH using 
E. coli and pTXB1 expression system. The open reading frame (ORF) of hGH gene includes 573 
base pairs was amplified by PCR cDNA clone, using specific primers containing restriction site 
terminals. The product was cloned into pTXB1 expression vector and transformed into BL21 
bacterial cells. The chitin-binding domain (CBD) present in the intein-tag of pTXB1, allowed for 
the affinity purification of the fusion protein using chitin beads.  The molecular weight of the 
purified protein was determined by SDS-PAGE which revealed a single band at 22 kDa. The 
purified protein identity was verified using mass spectrometry. Large scale recombinant protein 
production is becoming increasingly important for applications in the field of proteomics. This 
study is an initial step for large scale production of purified rhGH for medicinal use as a 
pharmaceutical product.