Description
IGF-I, IGF-II, insulin-like growth factors -1 and -2 are important regulators of signaling that mediates growth and metabolism in cells. Insulin-like growth factor -1 shares structural homology with proinsulin and is mainly produced by liver. IGF-1 acts via specific receptor, IGF-1R, a heterodimeric tyrosine kinase receptor that signals to various second messenger pathways such as MAPK, Raf/Ras and PI3K cascades. Tissue, pathway, proteinase, peptidase, protease ,acrosin, lipoprotein, activator, caspase, trypsin, papain, esterase inhibitors are proteins or receptor ligands or receptor antagonists that bind to an enzyme receptor and decreases its activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. Not all receptor antagonist that bind to enzymes are inhibitors; enzyme activator ligands or agonists bind to enzymes and increase their enzymatic activity, while enzyme substrates bind and are converted to products in the normal catalytic cycle of the enzyme.
