About Somatropin Synthetic human growth hormone, Treatment of growth hormone deficiency. Mechanism of Action of Somatropin It is a purified growth hormone (GH) of recombinant DNA origin that stimulates skeletal, linear bone, muscle, and organ growth. It promotes growth by inducing hyperplasia. It acts on cell surface receptors present on all cells. Binding of GH molecule to the extracellular domain of two growth hormone receptors induces their dimerization and activates intracellular domain through a single transmembrane peptide segment. The activated intracellular domain associated with cytoplasmic Jak2 tyrosin-protein kinase and phosphorylates relevant proteins which carry out various actions. The growth hormone also exerts indirect actions through elaboration of peptides called somatomedins or Insulin like growth factors (IGF-1, IGF-2) which are extracellular mediators of GH response. It causes proportionate increase in size and mass of all parts and promotes retention of nitroge