Current research on recombinant human growth hormone and the related growth factors, IGF-1 and GRF

A brief introduction is provided to the physiological actions of somatostatin, somatomedins and growth hormone releasing factor (GRF) in relation to human growth hormone (hGH). The development of recombinant DNA techniques allowed the biosynthesis of somatrem (methionyl hGH), and as the methods were refined, authentic recombinant hGH (methionyl-free) has been produced. rhGH is currently undergoing clinical trials in several countries. Recombinant IGF-1 has also been developed by similar methods, utilizing a yeast as the host cell. In contrast, GRF is too small to be biosynthesized, but can be produced by classical peptide synthesis. Only the N-terminal sequence is required for biological activity, and may be 29, 40 or 44 residues long. Research into the biological effects of both IGF-1 and GRF is underway.