Synthesis and Circulation
IGF-1 is produced primarily by the liver as an endocrine hormone as well as in target tissues in a paracrine/autocrine fashion. Production is stimulated by growth hormone (GH) and can be retarded by undernutrition, growth hormone insensitivity, lack of growth hormone receptors, or failures of the downstream signalling pathway post GH receptor including SHP2 and STAT5B. Approximately 98% of IGF-1 is always bound to one of 6 binding proteins (IGF-BP). IGFBP-3, the most abundant protein, accounts for 80% of all IGF binding. IGF-1 binds to IGFBP-3 in a 1:1 molar ratio.
In rat experiments the amount of IGF-1 mRNA in the liver was positively associated with dietary casein and negatively associated with a protein-free diet.
Recently, an efficient plant expression system was developed to produce biologically active recombinant human IGF-I (rhIGF-I) in transgenic rice grains.
Read more about this topic: Insulin-like Growth Factor 1
Famous quotes containing the words synthesis and/or circulation:
“If in the opinion of the Tsars authors were to be the servants of the state, in the opinion of the radical critics writers were to be the servants of the masses. The two lines of thought were bound to meet and join forces when at last, in our times, a new kind of regime the synthesis of a Hegelian triad, combined the idea of the masses with the idea of the state.”
—Vladimir Nabokov (1899–1977)
“There is probably not more than one hundred dollars in cash in circulation today. That is, if you were to call in all the bills and silver and gold in the country at noon tomorrow and pile them on the table, you would find that you had just about one hundred dollars, with perhaps several Canadian pennies and a few peppermint Life Savers.”
—Robert Benchley (1889–1945)