Molecular cloning of eel growth hormone cDNA and its expression in Escherichia coli

cDNA clones coding for growth hormone (eGH) of Japanese eel (Anguilla japonica) have been isolated from a cDNA library prepared from pituitary gland poly(A)+ RNA. The nucleotide sequence of the eGH cDNA was determined. It codes for the prehormone of 209 amino acids (aa) including a putative signal peptide of 19 aa. The deduced amino acid sequence was identical with that determined for eGH protein. The primary structure of eGH was compared with those of other species growth hormones (chum salmon, chicken, rat, and human). Mature eGH was expressed in Escherichia coli harboring a plasmid in which the eGH cDNA was under control of the phage lambda pL promoter. Recombinant eGH polypeptide was immunoreactive to rabbit antiserum against natural eGH. Furthermore, eGH derivative with amino-terminal deletion (delta 1-3 eGH) was produced in E. coli reaching up to 5% of total cellular proteins.