Insulin-like growth factor 1 (IGF-1) is a hormone with a molecular weight of 7.649 kDa and comprised of 70 amino acids and three disulfide bridges in a single chain. It has anabolic effects, promoting systemic body growth. In humans, it is encoded by the IGF1 gene on chromosome 12. As an endocrine hormone, it is produced by the liver and released into the bloodstream to reach target tissues (e.g. muscles, bones, cartilages, skin, hematopoietic cells, and lung cells). Its release is stimulated by the growth hormone. Its production peaks at puberty, especially during the growth spurt. It is one of the two ligands of insulin-type growth factors (IGF); the other is IGF-2. IGFs are characterized by having a considerable similarity to the amino acid sequence of insulin and they are capable of producing biological responses similar to insulin. IGF-1 is always bound to IGF-binding proteins (IGFBP), typically IGFBP-3. On the surface of target cells, it docks to the IGF-1 receptor and insulin receptor. Via IGF-1 receptor, IGF-1 activates intracellular signaling, such as the AKT signaling pathway. Abbreviation: IGF-1. Synonyms: somatomedin C, nonsuppressible insulin-like activity (NSILA).
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