Abstract: Pituitary growth hormone (GH) is essential for growth and metabolism in animals.Association of GH with the GH receptor (GHR) in target tissues of GH triggers the postreceptor signaling systems,which culminate in the biological actions of GH.GHR is a glycoprotein of about 620 amino acids (aa) with single transmembrane domain.The extracellular,the transmembrane and the intracellular domain of GHR are composed of about 245 aa,25 aa and 350 aa respectively.The pathways of signaling by GHR include the activations of the tyrosine kinase JAK2,the protein kinase C and the insulin receptor substrate.Nutrition,GH and other factors can also regulate the expression of GHR.